Genomes and Genes
Gene Symbol: SSA1
Description: Hsp70 family ATPase SSA1
Alias: YG100, Hsp70 family ATPase SSA1
Species: Saccharomyces cerevisiae S288c
- Krzewska J, Melki R. Molecular chaperones and the assembly of the prion Sup35p, an in vitro study. EMBO J. 2006;25:822-33 pubmed
- Fang N, Ng A, Measday V, Mayor T. Hul5 HECT ubiquitin ligase plays a major role in the ubiquitylation and turnover of cytosolic misfolded proteins. Nat Cell Biol. 2011;13:1344-52 pubmed publisher..These findings indicate that Hul5 is involved in a cytosolic protein quality control pathway that targets misfolded proteins for degradation. ..
- Nekrasov V, Smith M, Peak Chew S, Kilmartin J. Interactions between centromere complexes in Saccharomyces cerevisiae. Mol Biol Cell. 2003;14:4931-46 pubmed..These results show an increasingly complex structure for the S. cerevisiae centromere and a probable conservation of structure between parts of the centromeres of S. cerevisiae and S. pombe. ..
- Raviol H, Sadlish H, Rodriguez F, Mayer M, Bukau B. Chaperone network in the yeast cytosol: Hsp110 is revealed as an Hsp70 nucleotide exchange factor. EMBO J. 2006;25:2510-8 pubmed..This is the first report of a nucleotide exchange activity for the Hsp110 class of proteins, and provides a key piece in the puzzle of the cellular chaperone network. ..
- Sielaff B, Tsai F. The M-domain controls Hsp104 protein remodeling activity in an Hsp70/Hsp40-dependent manner. J Mol Biol. 2010;402:30-7 pubmed publisher..Our results demonstrate that the M-domain controls Hsp104 protein remodeling activities in an Hsp70/Hsp40-dependent manner, which is required to unleash Hsp104 protein disaggregating activity. ..
- Truman A, Kristjansdottir K, Wolfgeher D, Hasin N, Polier S, Zhang H, et al. CDK-dependent Hsp70 Phosphorylation controls G1 cyclin abundance and cell-cycle progression. Cell. 2012;151:1308-18 pubmed publisherIn budding yeast, the essential functions of Hsp70 chaperones Ssa1-4 are regulated through expression level, isoform specificity, and cochaperone activity...
- Fan C, Lee S, Ren H, Cyr D. Exchangeable chaperone modules contribute to specification of type I and type II Hsp40 cellular function. Mol Biol Cell. 2004;15:761-73 pubmed..Type I and type II Hsp40s, such as yeast Ydj1 and Sis1, form chaperone pairs with cytosolic Hsp70 Ssa1 that fold proteins with different efficiencies and carry out specific cellular functions...
- Sharma D, Masison D. Single methyl group determines prion propagation and protein degradation activities of yeast heat shock protein (Hsp)-70 chaperones Ssa1p and Ssa2p. Proc Natl Acad Sci U S A. 2011;108:13665-70 pubmed publisher..degradation pathway did not affect prion propagation, however, indicating these are two distinct processes where Ssa1/2p chaperones function differently...
- Meyer A, Hung N, Yang P, Johnson A, Craig E. The specialized cytosolic J-protein, Jjj1, functions in 60S ribosomal subunit biogenesis. Proc Natl Acad Sci U S A. 2007;104:1558-63 pubmed
- Werner Washburne M, Stone D, Craig E. Complex interactions among members of an essential subfamily of hsp70 genes in Saccharomyces cerevisiae. Mol Cell Biol. 1987;7:2568-77 pubmed..One subfamily, identified by sequence homology, contains four genes, SSA1, SSA2, SSA3, and SSA4 (formerly YG100, YG102, YG106, and YG107, respectively)...
- Mackay R, Helsen C, Tkach J, Glover J. The C-terminal extension of Saccharomyces cerevisiae Hsp104 plays a role in oligomer assembly. Biochemistry. 2008;47:1918-27 pubmed publisher..However, elimination of the whole C-terminal extension results in an Hsp104 molecule which is unable to assemble and becomes aggregation prone at high temperature, highlighting a novel structural role for this region. ..
- Albanèse V, Yam A, Baughman J, Parnot C, Frydman J. Systems analyses reveal two chaperone networks with distinct functions in eukaryotic cells. Cell. 2006;124:75-88 pubmed..The emergence of a translation-linked chaperone network likely underlies the elaborate cotranslational folding process necessary for the evolution of larger multidomain proteins characteristic of eukaryotic cells. ..
- Jones G, Song Y, Chung S, Masison D. Propagation of Saccharomyces cerevisiae [PSI+] prion is impaired by factors that regulate Hsp70 substrate binding. Mol Cell Biol. 2004;24:3928-37 pubmed..Earlier characterization of HSP70 (SSA1) mutations suggested that [PSI(+)] propagation is impaired by alterations that enhance Ssa1p's substrate binding...
- Halladay J, Craig E. A heat shock transcription factor with reduced activity suppresses a yeast HSP70 mutant. Mol Cell Biol. 1995;15:4890-7 pubmedStrains carrying deletions in both the SSA1 and SSA2 HSP70 genes of Saccharomyces cerevisiae exhibit pleiotropic phenotypes, including the inability to grow at 37 degrees C or higher, reduced growth rate at permissive temperatures, ..
- Newnam G, Wegrzyn R, Lindquist S, Chernoff Y. Antagonistic interactions between yeast chaperones Hsp104 and Hsp70 in prion curing. Mol Cell Biol. 1999;19:1325-33 pubmed..Here, we show that simultaneous overexpression of Ssa1, a protein of the Hsp70 family, protects [PSI] from curing by overexpression of Hsp104...
- Loovers H, Guinan E, Jones G. Importance of the Hsp70 ATPase domain in yeast prion propagation. Genetics. 2007;175:621-30 pubmed..Analysis of the effects of Hsp70 mutants upon propagation of a second yeast prion [URE3] further classifies these mutants as having general or prion-specific inhibitory properties. ..
- Oka M, Nakai M, Endo T, Lim C, Kimata Y, Kohno K. Loss of Hsp70-Hsp40 chaperone activity causes abnormal nuclear distribution and aberrant microtubule formation in M-phase of Saccharomyces cerevisiae. J Biol Chem. 1998;273:29727-37 pubmed..To elucidate the function of the yeast cytosolic hsp70 Ssa1p in vivo, we characterized a Saccharomyces cerevisiae ssa1 temperature-sensitive mutant (ssa1-134)...
- Andréasson C, Fiaux J, Rampelt H, Mayer M, Bukau B. Hsp110 is a nucleotide-activated exchange factor for Hsp70. J Biol Chem. 2008;283:8877-84 pubmed publisher..results in formation of a stabilized conformation of Sse1 that is required for association with the yeast Hsp70 Ssa1. The interaction triggers release of bound ADP from Ssa1, but nucleotide persists bound to Sse1 in the complex...
- Shulga N, James P, Craig E, Goldfarb D. A nuclear export signal prevents Saccharomyces cerevisiae Hsp70 Ssb1p from stimulating nuclear localization signal-directed nuclear transport. J Biol Chem. 1999;274:16501-7 pubmed..Elevated levels of SSA1 but not SSB1 suppressed the NLS-GFP nuclear localization defects of nup188-Delta cells...
- Shulga N, Roberts P, Gu Z, Spitz L, Tabb M, Nomura M, et al. In vivo nuclear transport kinetics in Saccharomyces cerevisiae: a role for heat shock protein 70 during targeting and translocation. J Cell Biol. 1996;135:329-39 pubmed..that the kinetics of NLS-directed nuclear transport in wild-type cells is stimulated by the elevated expression of SSA1, which encodes a cytoplasmic heat shock protein 70 (Hsp70)...
- Lopez Ribot J, Chaffin W. Members of the Hsp70 family of proteins in the cell wall of Saccharomyces cerevisiae. J Bacteriol. 1996;178:4724-6 pubmedWestern blot (immunoblot) analysis of cell wall and cytosolic extracts obtained from parental and ssa1 and ssa2 single- and double-mutant strains of Saccharomyces cerevisiae showed that the heat shock protein 70 (Hsp70) products of these ..
- Yam A, Albanèse V, Lin H, Frydman J. Hsp110 cooperates with different cytosolic HSP70 systems in a pathway for de novo folding. J Biol Chem. 2005;280:41252-61 pubmed..It, thus, appears that Hsp110 is an important regulator of Hsp70-substrate interactions. Based on our data, we propose that Hsp110 cooperates with the SSB and SSA Hsp70 subfamilies, which act sequentially during de novo folding. ..
- Bush G, Meyer D. The refolding activity of the yeast heat shock proteins Ssa1 and Ssa2 defines their role in protein translocation. J Cell Biol. 1996;135:1229-37 pubmedb>Ssa1/2p, members of one of the yeast cytosolic hsp70 subfamilies, have been implicated in the translocation of secretory proteins into the lumen of the ER...
- Bagriantsev S, Gracheva E, Richmond J, Liebman S. Variant-specific [PSI+] infection is transmitted by Sup35 polymers within [PSI+] aggregates with heterogeneous protein composition. Mol Biol Cell. 2008;19:2433-43 pubmed publisher..show that the major components of two different variants of [PSI(+)] are interacting infectious Sup35 polymers and Ssa1/2...
- Sondermann H, Ho A, Listenberger L, Siegers K, Moarefi I, Wente S, et al. Prediction of novel Bag-1 homologs based on structure/function analysis identifies Snl1p as an Hsp70 co-chaperone in Saccharomyces cerevisiae. J Biol Chem. 2002;277:33220-7 pubmed..Thus, Snl1p is the first Bag domain protein identified in S. cerevisiae, and its interaction with Hsp70 is essential for biological activity. ..
- Li J, Wu Y, Qian X, Sha B. Crystal structure of yeast Sis1 peptide-binding fragment and Hsp70 Ssa1 C-terminal complex. Biochem J. 2006;398:353-60 pubmed..by determining the crystal structure of yeast Hsp40 Sis1 peptide-binding fragment complexed with the Hsp70 Ssa1 C-terminal...
- Kabani M, Beckerich J, Brodsky J. Nucleotide exchange factor for the yeast Hsp70 molecular chaperone Ssa1p. Mol Cell Biol. 2002;22:4677-89 pubmed..In support of this hypothesis, Fes1p was found to be associated with ribosomes. ..
- Nakatsukasa K, Huyer G, Michaelis S, Brodsky J. Dissecting the ER-associated degradation of a misfolded polytopic membrane protein. Cell. 2008;132:101-12 pubmed publisher..These data indicate that polytopic membrane proteins can be extracted from the ER, and define the point of action of chaperones and the requirement for Ufd2p during membrane protein quality control...
- Becker J, Walter W, Yan W, Craig E. Functional interaction of cytosolic hsp70 and a DnaJ-related protein, Ydj1p, in protein translocation in vivo. Mol Cell Biol. 1996;16:4378-86 pubmed..70-kDa heat shock proteins (hsps) of Saccharomyces cerevisiae, we isolated a temperature-sensitive mutant of SSA1. The effect of a shift of mutant cells (ssa1ts ssa2 ssa3 ssa4) from the permissive temperature of 23 degrees C to ..
- Allen K, Wegrzyn R, Chernova T, Muller S, Newnam G, Winslett P, et al. Hsp70 chaperones as modulators of prion life cycle: novel effects of Ssa and Ssb on the Saccharomyces cerevisiae prion [PSI+]. Genetics. 2005;169:1227-42 pubmedPSI(+)] is a prion isoform of the yeast release factor Sup35. In some assays, the cytosolic chaperones Ssa1 and Ssb1/2 of the Hsp70 family were previously shown to exhibit "pro-[PSI(+)]" and "anti-[PSI(+)]" effects, ..
- Glover J, Lindquist S. Hsp104, Hsp70, and Hsp40: a novel chaperone system that rescues previously aggregated proteins. Cell. 1998;94:73-82 pubmed..coli. We conclude that Hsp104 has a protein remodeling activity that acts on trapped, aggregated proteins and requires specific interactions with conventional chaperones to promote refolding of the intermediates it produces. ..
- Shaner L, Wegele H, Buchner J, Morano K. The yeast Hsp110 Sse1 functionally interacts with the Hsp70 chaperones Ssa and Ssb. J Biol Chem. 2005;280:41262-9 pubmed..Sse1 stimulated Ssa1 ATPase activity synergistically with the co-chaperone Ydj1, and stimulation required complex formation...
- Wegele H, Haslbeck M, Reinstein J, Buchner J. Sti1 is a novel activator of the Ssa proteins. J Biol Chem. 2003;278:25970-6 pubmed..Using purified components, we reconstituted the dimeric Ssa1-Sti1 complex and the ternary Ssa1-Sti1-yHsp90 complex in vitro...
- Roberts T, Kobor M, Bastin Shanower S, Ii M, Horte S, Gin J, et al. Slx4 regulates DNA damage checkpoint-dependent phosphorylation of the BRCT domain protein Rtt107/Esc4. Mol Biol Cell. 2006;17:539-48 pubmed
- Song Y, Wu Y, Jung G, Tutar Y, Eisenberg E, Greene L, et al. Role for Hsp70 chaperone in Saccharomyces cerevisiae prion seed replication. Eukaryot Cell. 2005;4:289-97 pubmed..It is uncertain if polymers or higher-order aggregates or both act as prion seeds. A mutant Hsp70 chaperone, Ssa1-21p, reduces the number of transmissible [PSI+] seeds per cell by 10-fold but the overall amount of aggregated ..
- Keefer K, True H. Prion-Associated Toxicity is Rescued by Elimination of Cotranslational Chaperones. PLoS Genet. 2016;12:e1006431 pubmed publisher..This toxicity rescue demonstrates that chaperone modification can block key steps of the prion life cycle and has exciting implications for potential treatment of many human protein conformational disorders. ..
- Zhang S, Williams C, Hagan K, Peltz S. Mutations in VPS16 and MRT1 stabilize mRNAs by activating an inhibitor of the decapping enzyme. Mol Cell Biol. 1999;19:7568-76 pubmed..Intriguingly, the interaction with Ssa1p/2p is enhanced in strains with mutations in vps16 or mrt1. We propose that Hsp70s may be involved in the regulation of mRNA decapping. ..
- Scazzari M, Amm I, Wolf D. Quality control of a cytoplasmic protein complex: chaperone motors and the ubiquitin-proteasome system govern the fate of orphan fatty acid synthase subunit Fas2 of yeast. J Biol Chem. 2015;290:4677-87 pubmed publisher..The ubiquitin-conjugating enzymes Ubc2 and Ubc4 assist the degradation process. The AAA-ATPase Cdc48 and the Hsp70 chaperone Ssa1 are crucially involved in the elimination of Fas2.
- Lee R, Brunette S, Puente L, Megeney L. Metacaspase Yca1 is required for clearance of insoluble protein aggregates. Proc Natl Acad Sci U S A. 2010;107:13348-53 pubmed publisher..Together, our results show that Yca1 contributes to the fitness and adaptability of growing yeast through an aggregate remodeling activity. ..
- Hammack L, Firestone K, Chang W, Kusmierczyk A. Molecular chaperones of the Hsp70 family assist in the assembly of 20S proteasomes. Biochem Biophys Res Commun. 2017;486:438-443 pubmed publisher..Here, we demonstrate that two members of the Hsp70 family in yeast, Ssa1 and Ssa2, play a direct role in CP assembly...
- Keefer K, True H. A toxic imbalance of Hsp70s in Saccharomyces cerevisiae is caused by competition for cofactors. Mol Microbiol. 2017;105:860-868 pubmed publisher..For example, overexpression of Ssa1, a yeast Hsp70, is toxic to cells in folding-challenged states such as [PSI+]...
- Phan V, Ding V, Li F, Chalkley R, Burlingame A, McCormick F. The RasGAP proteins Ira2 and neurofibromin are negatively regulated by Gpb1 in yeast and ETEA in humans. Mol Cell Biol. 2010;30:2264-79 pubmed publisher..These findings provide evidence for conserved ubiquitination pathways regulating the RasGAP proteins Ira2 (in yeast) and neurofibromin (in humans). ..
- Wang R, Stork J, Pogany J, Nagy P. A temperature sensitive mutant of heat shock protein 70 reveals an essential role during the early steps of tombusvirus replication. Virology. 2009;394:28-38 pubmed publisher..The constitutively expressed SSA1 and SSA2, which are resident proteins in the viral replicase, can be complemented by the heat-inducible SSA3 and/or ..
- Serva S, Nagy P. Proteomics analysis of the tombusvirus replicase: Hsp70 molecular chaperone is associated with the replicase and enhances viral RNA replication. J Virol. 2006;80:2162-9 pubmed..The host proteins included the Ssa1/2p molecular chaperones (yeast homologues of Hsp70 proteins), Tdh2/3p (glyceraldehyde-3-phosphate dehydrogenase, an ..
- Garcia V, Nillegoda N, Bukau B, Morano K. Substrate binding by the yeast Hsp110 nucleotide exchange factor and molecular chaperone Sse1 is not obligate for its biological activities. Mol Biol Cell. 2017;28:2066-2075 pubmed publisher..We conclude that despite conservation among eukaryotic homologues, chaperone holdase activity is not an obligate function in the Hsp110 family. ..
- Jakobsson M, Davydova E, MaÅ‚ecki J, Moen A, Falnes P. Saccharomyces cerevisiae Eukaryotic Elongation Factor 1A (eEF1A) Is Methylated at Lys-390 by a METTL21-Like Methyltransferase. PLoS ONE. 2015;10:e0131426 pubmed publisher..Our results demonstrate that Ynl024c is the enzyme responsible for methylation of eEF1A at Lys390, and in accordance with prior naming of similar enzymes, we suggest that Ynl024c is renamed to Efm6 (Elongation factor MTase 6). ..
- Borggrefe T, Davis R, Erdjument Bromage H, Tempst P, Kornberg R. A complex of the Srb8, -9, -10, and -11 transcriptional regulatory proteins from yeast. J Biol Chem. 2002;277:44202-7 pubmed
- Albanèse V, Reissmann S, Frydman J. A ribosome-anchored chaperone network that facilitates eukaryotic ribosome biogenesis. J Cell Biol. 2010;189:69-81 pubmed publisher..Our results demonstrate that, in addition to their known cytoplasmic roles in de novo protein folding, some ribosome-anchored CLIPS chaperones play a critical role in nuclear steps of ribosome biogenesis. ..
- Truman A, Kristjansdottir K, Wolfgeher D, Ricco N, Mayampurath A, Volchenboum S, et al. Quantitative proteomics of the yeast Hsp70/Hsp90 interactomes during DNA damage reveal chaperone-dependent regulation of ribonucleotide reductase. J Proteomics. 2015;112:285-300 pubmed publisher..affinity-purification mass spectrometry (AP-MS) proteomics to characterize interactomes of the yeast Hsp70 isoform Ssa1 and Hsp90 isoform Hsp82 before and after exposure to methyl methanesulfonate...
- Yu H, Ziegelhoffer T, Osipiuk J, Ciesielski S, Baranowski M, Zhou M, et al. Roles of intramolecular and intermolecular interactions in functional regulation of the Hsp70 J-protein co-chaperone Sis1. J Mol Biol. 2015;427:1632-43 pubmed publisher..These interactions may be one means by which cells triage Ydj1- and Sis1-bound clients to productive and quality control pathways, respectively. ..
- Tutar Y, Arslan D, Tutar L. Heat, pH induced aggregation and surface hydrophobicity of S. cerevesiae Ssa1 protein. Protein J. 2010;29:501-8 pubmed publisher..For this purpose, S. cerevesiae cytosolic Hsp70 (Ssa1) biochemical properties were characterized...
- Hall M, Kunkel T. Purification of eukaryotic MutL homologs from Saccharomyces cerevisiae using self-affinity technology. Protein Expr Purif. 2001;21:333-42 pubmed..The general approach is a valid alternative for simple, rapid purification of recombinant proteins in yeast when expression in bacteria is unsuitable. ..
- Needham P, Masison D. Prion-impairing mutations in Hsp70 chaperone Ssa1: effects on ATPase and chaperone activities. Arch Biochem Biophys. 2008;478:167-74 pubmed publisher..b>Ssa1(L483W) ATPase activity was elevated 10-fold and was least stimulated by substrates or Hsp40 co-chaperones...
- Moriel Carretero M, Tous C, Aguilera A. Control of the function of the transcription and repair factor TFIIH by the action of the cochaperone Ydj1. Proc Natl Acad Sci U S A. 2011;108:15300-5 pubmed publisher..Our results provide evidence for a role of chaperones in NER and transcription, with implications in cancer and TFIIH-associated syndromes. ..
- Elbing K, McCartney R, Schmidt M. Purification and characterization of the three Snf1-activating kinases of Saccharomyces cerevisiae. Biochem J. 2006;393:797-805 pubmed..Finally, we showed that the Snf1 kinase domain isolated from bacteria as a GST fusion protein can be activated in vitro and shows substrate specificity in the absence of its beta and gamma subunits. ..
- Wang H, Garí E, Vergés E, Gallego C, Aldea M. Recruitment of Cdc28 by Whi3 restricts nuclear accumulation of the G1 cyclin-Cdk complex to late G1. EMBO J. 2004;23:180-90 pubmed..We propose that Whi3 constitutes a cytoplasmic retention device for Cln3-Cdc28 complexes, thus defining a key G1 event in yeast cells. ..
- Martineau C, Beckerich J, Kabani M. Flo11p-independent control of "mat" formation by hsp70 molecular chaperones and nucleotide exchange factors in yeast. Genetics. 2007;177:1679-89 pubmed..Furthermore, complex interactions among SSA genes were observed: mat formation depended mostly on SSA1 while minor defects were observed upon loss of SSA2; additional mutations in SSA3 or SSA4 further enhanced these ..
- Kochenova O, Bezalel Buch R, Tran P, Makarova A, Chabes A, Burgers P, et al. Yeast DNA polymerase ? maintains consistent activity and mutagenicity across a wide range of physiological dNTP concentrations. Nucleic Acids Res. 2017;45:1200-1218 pubmed publisher..The results support a model wherein dNTP elevation is needed to facilitate non-mutagenic tolerance pathways, while Pol? synthesis represents a unique mechanism of rescuing stalled replication when dNTP supply is low. ..
- Hon T, Lee H, Hach A, Johnson J, Craig E, Erdjument Bromage H, et al. The Hsp70-Ydj1 molecular chaperone represses the activity of the heme activator protein Hap1 in the absence of heme. Mol Cell Biol. 2001;21:7923-32 pubmed..Our results suggest that Ssa-Ydj1 and Sro9 act together to mediate Hap1 repression in the absence of heme and that molecular chaperones promote heme regulation of Hap1 by a mechanism distinct from the mechanism of steroid signaling. ..
- Liou S, Cheng M, Wang C. SGT2 and MDY2 interact with molecular chaperone YDJ1 in Saccharomyces cerevisiae. Cell Stress Chaperones. 2007;12:59-70 pubmed..However, it was not clear whether Sgt2 might have a similar capacity. Here, we showed that Ssa1/Ssa2 (yeast heat shock cognate [Hsc]70), Hsc82 (yeast Hsp90), and Hsp104 coprecipitated with Sgt2 from yeast ..
- Bylund G, Majka J, Burgers P. Overproduction and purification of RFC-related clamp loaders and PCNA-related clamps from Saccharomyces cerevisiae. Methods Enzymol. 2006;409:1-11 pubmed..This methodology yielded all clamp loaders in high yield and with high enzymatic activity. The yeast 9-1-1 checkpoint clamp, consisting of Rad17, Mec3, and Ddc1, was overproduced and purified in a similar manner. ..
- Matsumoto R, Nam H, Agrawal G, Kim Y, Iwahashi H, Rakwal R. Exploring novel function of yeast Ssa1/2p by quantitative profiling proteomics using NanoESI-LC-MS/MS. J Proteome Res. 2007;6:3465-74 pubmedIn the present study, we profiled proteins in ssa1/2 mutant and wild-type using one-dimensional gel electrophoresis coupled with liquid chromatography and mass spectrometry to reveal a total of 322 proteins...
- Kumar N, Gaur D, Masison D, Sharma D. The BAG homology domain of Snl1 cures yeast prion [URE3] through regulation of Hsp70 chaperones. G3 (Bethesda). 2014;4:461-70 pubmed publisher..Furthermore, the short amino-terminal extension of the BAG domain profoundly affects its function. ..
- Baranes Bachar K, Baranes Bacher K, Khalaila I, Ivantsiv Y, Lavut A, Voloshin O, et al. New interacting partners of the F-box protein Ufo1 of yeast. Yeast. 2008;25:733-43 pubmed publisher..We show directly that the UIMs are crucial for Ufo1 ubiquitylation in vivo, indicating that they facilitate turnover of SCF Ufo1 complexes. This allows recycling of the core subunits of the SCF complex and cell cycle progression. ..
- Qian X, Hou W, Zhengang L, Sha B. Direct interactions between molecular chaperones heat-shock protein (Hsp) 70 and Hsp40: yeast Hsp70 Ssa1 binds the extreme C-terminal region of yeast Hsp40 Sis1. Biochem J. 2002;361:27-34 pubmed..By using yeast Hsp40 Sis1 and yeast Hsp70 Ssa1 as our model proteins, we found that the Sis1 peptide-binding fragment interacts directly with the full-length Ssa1 ..