Ce gros livre est le fruit d’un travail collectif, réalisé à l’initiative de l’Agence nationale de recherche sur le sida et les hépatites virales (ANRS), par un collectif de treize chercheur-e-s (sociologues, démographes, épidémiologistes, psycho-sociologues, économistes). Un long questionnaire a été élaboré et soumis par téléphone par soixante et un enquêteurs de l’Institut de sondage Ipsos à plus de 12 000 personnes âgées de 18 à 69 ans entre septembre 2005 et mars 2006. Cette enquête dite...

Durant les années 1950 et plus encore la décennie suivante, les ouvrages sur les questions féminines se multiplient. Cet article s’interroge sur les auteures de ces essais. Se dessine ainsi une génération d’expertes en études sur les femmes. Nées au début du siècle, profondément marquées par l’expérience de la deuxième guerre, ces nouvelles spécialistes sont diplômées des universités. Elles bénéficient de l’essor des médias mais ne parviennent pas toujours à avoir une situation professionnelle stable. Ensemble et s’appuyant sur les réflexions (...) beauvoiriennes, elles construisent un nouveau champ d’études, dont nous sommes les héritières. (shrink)

Dès que Le Deuxième sexe de Simone de Beauvoir paraît en France en 1949, il est pris dans la division intellectuelle de la guerre froide. Mais est-ce le cas dans le reste de l’Europe à mesure que les traductions du livre paraissent? Une comparaison des réceptions et traductions du livre au cours de la guerre froide manque. Elle est pourtant rendue possible grâce à trois récents tournants historiographiques : la guerre froide au prisme du genre, l’étude des circulations transnationales du (...) Deuxième sexe et la traductologie féministe. (shrink)

L'histoire des femmes depuis la Seconde Guerre mondiale est bien plus développée en Italie qu'en France. Le dernier ouvrage d'Anna Rossi-Doria nous en fournit une preuve supplémentaire. S'appuyant sur ses recherches personnelles, mais aussi sur une solide bibliographie, l'auteure s'interroge sur les multiples facettes du droit de vote féminin. Le décret qui institue le droit de vote féminin présente bien des similarités avec l'ordonnance française. Comme en France, celui-ci ne résulte..

Depuis les années 1980, l’histoire de la médecine a connu un très fort renouvellement de ses approches, de ses objets et de sa mise en récit. L’histoire des femmes, du genre et des sexualités, en plein essor depuis ces mêmes années, a contribué de manière non négligeable à ce renouvellement en s’emparant de sources médicales délaissées par l’histoire de la médecine traditionnelle. En effet, durablement imprégnées par l’héritage positiviste du xixe siècle, l’histoire de la médecine et plus lar...

This article explores the critical reception of The Second Sex in France in 1949. Situating debates about the book in the context of the Cold War and the intellectual hegemony of existentialism, the author analyzes the main points of disagreement among different political factions—traditional Catholics, communists, members of the noncommunist left, and progressive Christians. She argues that the sexual questions Simone de Beauvoir raised in the public sphere fueled the primary points of contention.

Yvonne Knibiehler continue son histoire des mères commencée il y a quelques années et arrêtée au seuil des ses propres enfantements, comme elle le rappelle dans l'introduction. L'entreprise n'est pourtant pas aisée. Non pas que le sujet déborderait trop sur l'intime de la chercheuse. L'égo-histoire, qui ne rime décidément pas avec l'histoire tout court, ne dépasse pas les premières pages de l'ouvrage. Mais le sujet est miné, piégé de l'intérieur par une charge idéologique hors du commu..

Exceptionnel, l'itinéraire politique de Marcelle Devaud, l'est assurément. Sénatrice dès 1946 puis députée (de 1958 à 1962), maire de Colombes (1959-1965), membre de Conseil Economique et Social (1962-1979), représentante de la France à la commission de la femme aux Nations-Unies (1975-1983), elle cumule tous ces mandats avec de nombreuses responsabilités dans les associations féminines, dont plusieurs fondées par elle-même. Quand on sait qu'elle est par ailleurs mère de 6 enfants, on ..

L'ouvrage de William Guéraiche s'inscrit dans un renouvellement notable de l'historiographie de ces quelques dernières années. L'après-Deuxième Guerre mondiale, les années cinquante se voient revisitées de multiples façons par les travaux de Noël Burch et Geneviève Sellier, Luc Capdevila, Fabrice Virgili et moi-même. Le découpage chronologique de l'étude ne suit pas les coupures majeures de l'histoire politique française; ni 1958 ni 1968 ne fondent de ruptures, par exemple. La superpos...

Résumé Michèle Le Dœuff est une philosophe qui a beaucoup contribué aux études beauvoiriennes, mais dont l’ apport a été sous-évalué. Pourtant, Le Dœuff a été la première à faire un travail critique, philosophique et féministe autour du Deuxième Sexe, d’ abord dans son célèbre article « Cheveux longs, idées courtes » (1977), puis de façon plus approfondie dans L’ Étude et le rouet (1989). Les études beauvoiriennes ont sans doute encore beaucoup à puiser dans l’ œuvre de Le Dœuff.

Sans prétendre faire œuvre exhaustive ni même définitive, Mariette Sineau et Evelyne Tardy se livrent à un instructif travail comparatif sur le droit des femmes dans les deux territoires francophones. Malgré toutes leurs différences, ceux-ci se montrent suffisamment proches pour soutenir la comparaison. Tous deux adoptent le code civil napoléonien (en 1866 pour le Québec pourtant cerné par la bien plus progressive common law), tous deux sont également à forte dominante catholique. Le m..

Cet ouvrage reprend sous forme remaniée les actes du colloque « Germaine Poinso-Chapuis, témoin de son temps » organisé à Marseille par l'association Les Femmes et la Ville (20-22 novembre 1997). Il répare heureusement l'oubli injuste d'une figure majeure de l'histoire de l'après-guerre. Moins connue que les femmes sous-secrétaires d'État du Front populaire alors qu'elle est la première femme ministre de plein exercice, moins populaire que Simone Veil alors qu'elle a été députée pendan...

Pour celles et ceux qui ne connaîtraient pas ou peu, ou mal Marie-France Brive, ce livre offre l'occasion de multiples rencontres émouvantes avec l'une des figures majeures de l'histoire des femmes en France. Car, comme son titre ne l'indique pas, cet ouvrage collectif est un hommage posthume. Ironie de l'histoire, le nom de celle qui affirmait : « il y a une construction de l'oubli des femmes en histoire » (p. 333) se trouve ainsi effacé de la couverture du livre (...) qui lui est consacré.... (shrink)

Histone variants are specialized histones which replace their canonical counterparts in specific nucleosomes. Together with histone post‐translational modifications and DNA methylation, they contribute to the epigenome. Histone variants are incorporated at specific locations by the concerted action of histone chaperones and ATP‐dependent chromatin remodelers. Recent studies have shown that the histone chaperone FACT plays key roles in preventing pervasive incorporation of two histone variants: H2A.Z and CenH3/CENP‐A. In addition, Spt6, another histone chaperone, was also shown to be important (...) for appropriate H2A.Z localization. FACT and Spt6 are both associated with elongating RNA polymerase II. Based on these two examples, we propose that the establishment and maintenance of histone variant genomic distributions depend on a transcription‐coupled epigenome editing (or surveillance) function of histone chaperones. (shrink)

Molecular chaperones assist de novo protein folding and facilitate the refolding of stress‐denatured proteins. The molecular chaperone concept was coined nearly 35 years ago, and since then, tremendous strides have been made in understanding how these factors support protein folding. Here, we focus on how various chaperone proteins were first identified to play roles in protein folding. Examples are used to illustrate traditional routes of chaperone discovery and point out their advantages and limitations. Recent advances, including the (...) development of folding biosensors and promising methods for the stabilization of proteins in vivo, provide new routes for chaperone discovery. (shrink)

Fibrillar protein aggregates are the pathological hallmark of a group of age‐dependent neurodegenerative conditions, including Alzheimer's and Parkinson's disease. Aggregates of the microtubule‐associated protein Tau are observed in Alzheimer's disease and primary tauopathies. Tau pathology propagates from cell to cell in a prion‐like process that is likely subject to modulation by extracellular chaperones such as Clusterin. We recently reported that Clusterin delayed Tau fibril formation but enhanced the activity of Tau oligomers to seed aggregation of endogenous Tau in a cellular (...) model. In contrast, Clusterin inhibited the propagation of α‐Synuclein aggregates associated with Parkinson's disease. These findings raise the possibility of a mechanistic link between Clusterin upregulation observed in Alzheimer's disease and the progression of Tau pathology. Here we review the diverse functions of Clusterin in the pathogenesis of neurodegenerative diseases, focusing on evidence that Clusterin may act either as a suppressor or enhancer of pathology. (shrink)

Self‐renewal and differentiation of stem cells are tightly regulated processes subject to intrinsic and extrinsic signals. Molecular chaperones and co‐chaperones, especially heat shock proteins (Hsp), are ubiquitous molecules involved in the modulation of protein conformational and complexation states. The function of Hsp, which are typically associated with stress response and tolerance, is well characterized in differentiated cells, while their role in stem cells remains unclear. It appears that embryonic stem cells exhibit increased stress tolerance and concomitant high levels of (...) class='Hi'>chaperone expression. This review critically evaluates stem cell research from a molecular chaperone perspective. Furthermore, we propose a model of chaperone‐modulated self‐renewal in mouse embryonic stem cells. (shrink)

The discovery of “molecular chaperones” has dramatically changed our concept of cellular protein folding. Rather than folding spontaneously, most newly synthesized polypeptide chains seem to acquire their native conformation in a reaction mediated by these versatile helper proteins. Understanding the structure and function of molecular chaperones is likely to yield useful applications for medicine and biotechnology in the future.

Le mot sexologie, la science de la sexualité, apparaît en France au début des années 1910. Il marque, de la part de ceux qui en usent, la volonté à la fois de lutter pour l’égalité des droits en matière de pratiques sexuelles et de rompre avec le savoir médical sur la sexualité. Dans son livre Les origines de la sexologie, 1850-1900, Sylvie Chaperon explore ce champ nouveau de l’histoire et se propose de démêler les fils qui, en ce domaine, enchevêtrent (...) si fortement savoir, pouvoir et représe... (shrink)

We highlight a recent study exploring the hand‐off of UV damage to several key nucleotide excision repair (NER) proteins in the cascade: UV‐DDB, XPC and TFIIH. The delicate dance of DNA repair proteins is choreographed by the dynamic hand‐off of DNA damage from one recognition complex to another damage verification protein or set of proteins. These DNA transactions on chromatin are strictly chaperoned by post‐translational modifications (PTM). This new study examines the role that ubiquitylation and subsequent DDB2 degradation has during (...) this process. In total, this study suggests an intricate cellular timer mechanism that under normal conditions DDB2 helps recruit and ubiquitylate XPC, stabilizing XPC at damaged sites. If DDB2 persists at damaged sites too long, it is turned over by auto‐ubiquitylation and removed from DNA by the action of VCP/p97 for degradation in the 26S proteosome. (shrink)

Background: Medical chaperones (MC) are underutilised. The influence of Islamic culture on the use of MC is not known. Aim: To examine physicians’ use and perception of MC in Islamic culture. Setting: A major tertiary care hospital in Saudi Arabia. Methods: 315 self-administered questionnaires were distributed to attendees of grand rounds of 13 departments. Results: 186 (59%) questionnaires were completed. 64.5% of the respondents were 30–49 years old, 75.8% were men and 31.2% were in training; 79% had a clinic load (...) of under 50 patients per week and 47.8% had postgraduate training (PGT) in an Islamic country. MC were reported to be infrequently (⩽25% of the time) used by 44.1% (69.2% female vs 39% male physicians, p = 0.001; 58.6% in training vs 36.8% attending, p = 0.007; 52.1% PGT in Islamic vs 35.6% in western countries, p = 0.027), offered by 52.7% (78.9% female vs 46.8% male physicians, p<0.001) and requested by 79% of patients. MC were reported to be commonly (>75% of the time) used, offered by physicians and requested by patients by 38.2%, 29% and 7.5% of respondents, respectively. The most frequently cited reasons for not using MC were privacy/confidentiality (36.6%) and understaffing (30.5%). Equal numbers of respondents perceived MC use as a protection for physicians or patients (67.7% and 65.6%, respectively). Conclusions: MC are underutilised even in Islamic culture, especially among female physicians. Training in western countries is favourably associated with MC use. Underutilisation appears to be related to privacy/confidentiality, understaffing and failure of patients to request a MC. (shrink)

In this paper I use a case study—the discovery of the chaperon function exerted by proteins in the various steps of the hereditary process—to re-discuss the question whether the nucleic acids are the sole repositories of relevant information as assumed in the information theory of heredity. The evidence I here present of a crucial role for molecular chaperones in the folding of nascent proteins, as well as in DNA duplication, RNA folding and gene control, suggests that the family of proteins (...) acting as molecular chaperones provides information that is complementary to that stored in the nucleic acids, and equally important. A re-evaluation of the role of proteins in the hereditary process is in order away from the gene-centric approach of the information theory of heredity, to which neo-Darwinian evolutionists adhere. (shrink)

L’ouvrage présente une anthologie de quarante huit cas de perversions féminines publiés par vingt-quatre médecins différents du xixe siècle, précédés d’une introduction de vingt pages et se concluant par une bibliographie de trois pages. Les cas sont classés selon les termes de l’époque dans l’ordre suivant : onanisme (12 cas), nymphomanie (13), érotomanie (5), anaphrodisme, frigidité et impuissance (1), bestialité, zoophilie (2), nécrophilie (1), exhibitionnisme (1), saphisme, tribadisme et...

Cet ouvrage comble un vide dans l'histoire des femmes et du féminisme, qui ne s'était guère intéressée jusqu'ici à la période qui va de 1945 à 1970, à l'exception de travaux comme ceux de Dominique Loiseau sur le militantisme des femmes à Nantes ou notre recherche commune ­ Michelle Zancarini-Fournel et moi-même ­ sur des parcours de femmes à Saint-Étienne, incluant les années 1950. Grâce à ce livre, nous disposons maintenant, d'une bibliographie assez complète sur le féminisme françai...

This paper develops previous work on theories of embodiment by drawing on empirical data from a study into the experiences of infertile women in the UK. I suggest experiences of embodiment shape the preferences of infertile women for a female nurse as chaperone during intimate medical procedures. I explore the impact of this role on the understandings and meanings of nursing in a highly gendered field of practice. I present data from an ethnographic study of infertile women who chose (...) to attend a British infertility clinic for investigation and fertility treatment cycles. Data were collected over 2 years using participant observation and semistructured interviews with 15 women and 20 members of staff in a British fertility unit. Data analysis was completed using a modified thematic analysis following Boyle and McEvoy. I discuss women's experiences of intimacy and bodily care and how these experiences might be understood by exploring the phenomenological concept of embodiment. I argue that women benefit from having a female nurse as chaperone because of their expectations of gender, nursing and caring. Women's expectations reinforce both notions of gendered caring and the gendered role of nursing. These data challenge notions of patriarchal professionalism prevalent in nursing, which seek to move away from the gendered role of the nurse (which traditionally included a chaperone role) towards a model of professional development based on a mind–body split. I suggest that these data offer a way of understanding the female embodied subject in the field of gendered caring, which is potentially transgressive because they suggest ways in which both mind and body can be integrated through the role of the female chaperone. (shrink)

Resistance to inhibitors of cholinesterase 8A (Ric‐8A) is a prominent non‐receptor GEF and a chaperone of G protein α‐subunits (Gα). Recent studies shed light on the structure of Ric‐8A, providing insights into the mechanisms underlying its interaction with Gα. Ric‐8A is composed of a core armadillo‐like domain and a flexible C‐terminal tail. Interaction of a conserved concave surface of its core domain with the Gα C‐terminus appears to mediate formation of the initial Ric‐8A/GαGDP intermediate, followed by the formation of (...) a stable nucleotide‐free complex. The latter event involves a large‐scale dislocation of the Gα α5‐helix that produces an extensive primary interface and disrupts the nucleotide‐binding site of Gα. The distal portion of the C‐terminal tail of Ric‐8A forms a smaller secondary interface, which ostensibly binds the switch II region of Gα, facilitating binding of GTP. The two‐site Gα interface of Ric‐8A is distinct from that of GPCRs, and might have evolved to support the chaperone function of Ric‐8A. (shrink)

Basic proteins and nucleic acids are assembled into complexes in a reaction that must be facilitated by nuclear chaperones in order to prevent protein aggregation and formation of non‐specific nucleoprotein complexes. The nucleophosmin/nucleoplasmin (NPM) family of chaperones [NPM1 (nucleophosmin), NPM2 (nucleoplasmin) and NPM3] have diverse functions in the cell and are ubiquitously represented throughout the animal kingdom. The importance of this family in cellular processes such as chromatin remodeling, genome stability, ribosome biogenesis, DNA duplication and transcriptional regulation has led to (...) the rapid growth of information available on their structure and function. The present review covers different aspects related to the structure, evolution and function of the NPM family. Emphasis is placed on the long‐term evolutionary mechanisms leading to the functional diversification of the family members, their role as chaperones (particularly as it pertains to their ability to aid in the reprogramming of chromatin), and the importance of NPM2 as an essential component of the amphibian chromatin remodeling machinery during fertilization and early embryonic development. BioEssays 29: 49–59, 2007. © 2006 Wiley Periodicals, Inc. (shrink)

It is generally accepted that prion infection is due solely to a protein i.e. the protein-only hypothesis. The essential constituent of infectious prions is the scrapie prion protein (PrPSc) which is chemically indistinguishable from the normal, cellular protein (PrPC) but exhibits distinct secondary and tertiary structure. This very unusual feature seems to be in contradiction with a major paradigm of present structural biology stated by Anfinsen: a protein folds to the most stable conformation, this means only one structure.In order to (...) reconcile the results obtained on prions with the biophysics of protein folding, a model is proposed. It is based on the hypothesis that a thermodynamically irreversible step is involved in protein folding. The model is then extended to chaperone-assisted protein folding. It is shown that, under certain conditions, the transitory secondary structure formed during the earlier step of folding could interact with chaperone. Analysis shows that chaperone may help the protein to find correct conformation. On the other hand, analysis reveals the possibility that more than one structure may form from a single polypeptide chain. Under these conditions, the behaviour of chaperones resembles the characteristics of prion diseases. (shrink)

Objective To ascertain and improve the understanding and use of chaperones among the patients of an English general practice (GP). Background Doctors have long been advised to have a third party present during intimate physical examinations. Little is known about the understanding of the term in the general population in England and the consequences of this for the promotion and use of chaperones in GP. We audited the understanding and use of chaperones in an English GP. The aim of the (...) study was to increase the awareness of the availability of chaperones in our population. Methods A questionnaire was given randomly to 100 patients attending the GP surgery. Participants were asked about their awareness of and frequency of requesting a chaperone while undergoing intimate examinations. Based on the initial results, a poster was designed for the waiting room to increase awareness. Data were collected with the same questionnaire to see if the new poster altered surgery attendees understanding and likely subsequent use of chaperones. Results In the initial audit, 29% of patients were unaware of the term chaperone, and only one person (1%) had ever requested a chaperone. After the introduction of a specially designed poster, the results showed an improvement in awareness from 71% to 89%, and the likely frequency of using a chaperone increased from 1% to 4%. Conclusion There is a need to improve the understanding of the general population about chaperones if we are to see greater use of chaperones in GP. (shrink)

The mammalian egg employs a wide spectrum of epigenome modification machinery to reprogram the sperm nucleus shortly after fertilization. This event is required for transcriptional activation of the paternal/zygotic genome and progression through cleavage divisions. Reprogramming of paternal nuclei requires replacement of sperm protamines with canonical and non‐canonical histones, covalent modification of histone tails, and chemical modification of DNA (notably oxidative demethylation of methylated cytosines). In this essay we highlight the role maternal histone variants play during developmental reprogramming following fertilization. (...) We discuss how reduced maternal histone variant incorporation in somatic nuclear transfer experiments may explain the reduced viability of resulting embryos and how knowledge of repressive and activating maternal factors may be used to improve somatic cell reprogramming. (shrink)

This essay takes—as its point of departure—Cavicchi’s (2006) argument that knowledge develops through experimentation, both in science and in educational settings. In attempting to support and extend her conclusions, which are drawn in part from the replication of some early tasks in the history of developmental psychology, the late realist-constructivist theory of Jean Piaget is presented and summarized. This is then turned back on the subjects of Cavicchi’s larger enquiry (education and science) to offer a firmer foundation for future debate. (...) Several of Piaget’s “forgotten works” are discussed; their theoretical contributions synthesized to form a single interdisciplinary, cross-pollinating narrative describing how it is that both children and scientists grow into the world. (In addition, translated excerpts from two related historical documents have been provided in an appendix, while detailed footnotes add further context and integrate the discussion with current advances in related fields.). (shrink)

Molecular chaperones in cells constantly monitor and bind to exposed hydrophobicity in newly synthesized proteins and assist them in folding or targeting to cellular membranes for insertion. However, proteins can be misfolded or mistargeted, which often causes hydrophobic amino acids to be exposed to the aqueous cytosol. Again, chaperones recognize exposed hydrophobicity in these proteins to prevent nonspecific interactions and aggregation, which are harmful to cells. The chaperone‐bound misfolded proteins are then decorated with ubiquitin chains denoting them for proteasomal (...) degradation. It remains enigmatic how molecular chaperones can mediate both maturation of nascent proteins and ubiquitination of misfolded proteins solely based on their exposed hydrophobic signals. In this review, we propose a dynamic ubiquitination and deubiquitination model in which ubiquitination of newly synthesized proteins serves as a “fix me” signal for either refolding of soluble proteins or retargeting of membrane proteins with the help of chaperones and deubiquitinases. Such a model would provide additional time for aberrant nascent proteins to fold or route for membrane insertion, thus avoiding excessive protein degradation and saving cellular energy spent on protein synthesis. Also see the video abstract here: https://youtu.be/gkElfmqaKG4. (shrink)

Protein disulfide isomerase (PDI) is one of the most abundant and critical protein folding catalysts in the endoplasmic reticulum of eukaryotic cells. PDI consists of four thioredoxin domains and interacts with a wide range of substrate and partner proteins due to its intrinsic conformational flexibility. PDI plays multifunctional roles in a variety of pathophysiological events, both as an oxidoreductase and a molecular chaperone. Recent studies have revealed that the conformation and activity of PDI can be regulated in multiple ways, (...) including posttranslational modification and substrate/ligand binding. Here, we summarize recent advances in understanding the function and regulation of PDI in different pathological and physiological events. We propose that the multifunctional roles of PDI are regulated by multiple mechanisms. Furthermore, we discuss future directions for the study of PDI, emphasizing how different regulatory modes are linked to the conformational changes and biological functions of PDI in the context of diverse pathophysiologies. (shrink)

Regulation of microtubule (MT) dynamics is essential for many cellular processes, but the machinery that controls MT dynamics remains poorly understood. MT plus‐end tracking proteins (+TIPs) are a set of MT‐associated proteins that dynamically track growing MT ends and are uniquely positioned to govern MT dynamics. +TIPs associate with each other in a complex array of inter‐ and intra‐molecular interactions known as the “+TIP network.” Why do so many +TIPs bind to other +TIPs? Typical answers include the ideas that these (...) interactions localize proteins where they are needed, deliver proteins to the cortex, and/or create regulatory pathways. We propose an additional and more mechanistic hypothesis: that +TIPs bind each other to create a superstructure that promotes MT assembly by constraining the structural fluctuations of the MT tip, thus acting as a polymerization chaperone. (shrink)

This review portraits FK506 binding protein (FKBP) 51 as “reactivity protein” and collates recent publications to develop the concept of FKBP51 as contributor to different levels of adaptation. Adaptation is a fundamental process that enables unicellular and multicellular organisms to adjust their molecular circuits and structural conditions in reaction to environmental changes threatening their homeostasis. FKBP51 is known as chaperone and co‐chaperone of heat shock protein (HSP) 90, thus involved in processes ensuring correct protein folding in response to (...) proteotoxic stress. In mammals, FKBP51 both shapes the stress response and is calibrated by the stress levels through an ultrashort molecular feedback loop. More recently, it has been linked to several intracellular pathways related to the reactivity to drug exposure and stress. Through its role in autophagy and DNA methylation in particular it influences adaptive pathways, possibly also in a transgenerational fashion.Also see the video abstract here. (shrink)

Molecular chaperones facilitate the correct folding of other proteins under physiological and stress conditions. Recently it has become evident that various co‐chaperone proteins regulate the cellular functions of these chaperones, particularly Hsp70 and Hsp90. Hop is one of the most extensively studied co‐chaperones that is able to directly associate with both Hsp70 and Hsp90. The current dogma proposes that Hop functions primarily as an adaptor that directs Hsp90 to Hsp70‐client protein complexes in the cytoplasm. However, recent evidence suggests that (...) Hop can also modulate the chaperone activities of these Hsps, and that it is not dedicated to Hsp70 and Hsp90. While the co‐chaperone function of Hop within the cytoplasm has been extensively studied, its association with nuclear complexes and prion proteins remains to be elucidated. This article will review the structural features of Hop, and the evidence that its biological function is considerably broader than previously envisaged. BioEssays 26:1058–1068, 2004. © 2004 Wiley Periodicals, Inc. (shrink)

The environmentally responsive molecular chaperone Hsp90 assists the maturation of many key regulatory proteins. An unexpected consequence of this essential biochemical function is that genetic variation can accumulate in genomes and can remain phenotypically silent until Hsp90 function is challenged. Notably, this variation can be revealed by modest environmental change, establishing an environmentally responsive exposure mechanism. The existence of diverse cryptic polymorphisms with a plausible exposure mechanism in evolutionarily distant lineages has implications for the pace and nature of evolutionary (...) change. Chaperone‐mediated storage and release of genetic variation is undoubtedly rooted in protein‐folding phenomena. As we discuss, proper protein folding crucially affects the trajectory from genotype to phenotype. Indeed, the impact of protein quality‐control mechanisms and other fundamental cellular processes on evolution has heretofore been overlooked. A true understanding of evolutionary processes will require an integration of current evolutionary paradigms with the many new insights accruing in protein science. BioEssays 26:348–362, 2004. © 2004 Wiley Periodicals, Inc. (shrink)

Clp ATPase chaperone proteins are found in procaryotes and eucaryotes. Recently, ClpC of Bacillus subtilis was found to be part of a regulatory switch(1). ClpC, in combination with the MecA and ComS proteins, regulates the activity of a transcription factor, ComK, which is necessary for the development of genetic competence (the ability to bind and take up exogenous DNA). The complex of ClpC:MecA:ComK renders ComK inactive. Interaction between ComS and the ternary complex releases active ComK. This regulatory switch controls (...) ComK activity in response to cell density signals that affect production of ComS. Regulated interaction between Clp ATPases and target proteins might prove to be widespread. (shrink)