SSE2/YBR169C Summary Help

Standard Name SSE2
Systematic Name YBR169C
Feature Type ORF, Verified
Description Member of the heat shock protein 70 (HSP70) family; may be involved in protein folding; localized to the cytoplasm; SSE2 has a paralog, SSE1, that arose from the whole genome duplication (1, 2, 3 and see Summary Paragraph)
Chromosomal Location
ChrII:575996 to 573915 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Gene Ontology Annotations All SSE2 GO evidence and references
  View Computational GO annotations for SSE2
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Regulators 11 genes
Classical genetics
Large-scale survey
80 total interaction(s) for 53 unique genes/features.
Physical Interactions
  • Affinity Capture-MS: 33
  • Affinity Capture-RNA: 2
  • Affinity Capture-Western: 14
  • Biochemical Activity: 4
  • PCA: 2
  • Reconstituted Complex: 1

Genetic Interactions
  • Dosage Rescue: 3
  • Negative Genetic: 14
  • Phenotypic Suppression: 2
  • Positive Genetic: 1
  • Synthetic Growth Defect: 1
  • Synthetic Lethality: 3

Expression Summary
Length (a.a.) 693
Molecular Weight (Da) 77,620
Isoelectric Point (pI) 5.38
Phosphorylation PhosphoGRID | PhosphoPep Database
sequence information
ChrII:575996 to 573915 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Last Update Coordinates: 2011-02-03 | Sequence: 1997-01-28
Subfeature details
Most Recent Updates
Coordinates Sequence
CDS 1..2082 575996..573915 2011-02-03 1997-01-28
Retrieve sequences
Analyze Sequence
S288C only
S288C vs. other species
S288C vs. other strains
External Links All Associated Seq | Entrez Gene | Entrez RefSeq Protein | MIPS | Search all NCBI (Entrez) | UniProtKB
Primary SGDIDS000000373

SSE1 and SSE2 encode chaperonins that are in the Hsp110 subclass of HSP70 proteins (1). HSP70 is a large family of proteins that has been evolutionarily conserved from bacteria (DnaK) to humans (HSP72/73). HSP70 proteins were originally classified based upon their induction by heat shock and their size of ~70kDa. The main function of these proteins is to serve as molecular chaperones, binding newly-translated proteins to assist in proper folding and prevent aggregation/misfolding (reviewed in 4 and 5). SSE1 and SSE2 are two of nine cytosolic forms of HSP70 found in S. cerevisiae (SSA1, SSA2, SSA3, SSA4, SSB1, SSB2, SSE1, SSE2, SSZ1).

SSE is the yeast homolog of mammlian HSP110; the SSE/HSP110 subclass is only found in eukaryotic cells. It appears that the main function of these proteins is to act as nucleotide exchange factors (NEF) for HSP70 chaperones during protein refolding (6, 7). Additionally, independent of their NEF activity, these proteins can bind unfolded peptides and act as a 'holdase', maintaining their substrates in a folding-competent state by preventing misfolding/aggregation (reviewed in 8). Sse protein function has also been implicated in PKA signaling and HSP90 chaperone complex activity (9, 10).

SSE1 and SSE2 are 76% identical to each other and share 70% similarity with the HSP70 subfamily SSA (1). Like all other Hsp70 proteins, Sse1p and Sse2p contain an N-terminal ATPase domain and a C-terminal peptide-binding domain, but unlike other HSP70s, these domains have been shown to function and interact in trans (2). ATPase activity of Sse1p is stimulated by the DnaJ/HSP40 co-chaperone Sis1p (11). The Sse ATPase domain is also required for Sse1p to interact with Ssa1p and Ssb1p (6). Expression of SSE1 and SSE2 is induced by heat shock via the transcriptional factor Hsf1p, which binds to a heat shock element in the SSE gene promoter (1, 10). Deletion of SSE1 derepresses Hsf1p activity and also decreases cell growth rate, while sse2 null mutations have no discernable phenotype, and loss of both gene products results in lethality (10, 2, 1).

Last updated: 2006-02-07 Contact SGD

References cited on this page View Complete Literature Guide for SSE2
1) Mukai H, et al.  (1993) Isolation and characterization of SSE1 and SSE2, new members of the yeast HSP70 multigene family. Gene 132(1):57-66
2) Shaner L, et al.  (2004) The function of the yeast molecular chaperone Sse1 is mechanistically distinct from the closely related hsp70 family. J Biol Chem 279(21):21992-2001
3) Byrne KP and Wolfe KH  (2005) The Yeast Gene Order Browser: combining curated homology and syntenic context reveals gene fate in polyploid species. Genome Res 15(10):1456-61
4) Bukau B and Horwich AL  (1998) The Hsp70 and Hsp60 chaperone machines. Cell 92(3):351-66
5) Becker J and Craig EA  (1994) Heat-shock proteins as molecular chaperones. Eur J Biochem 219(1-2):11-23
6) Shaner L, et al.  (2005) The yeast Hsp110 Sse1 functionally interacts with the Hsp70 chaperones Ssa and Ssb. J Biol Chem 280(50):41262-9
7) Dragovic Z, et al.  (2006) Molecular chaperones of the Hsp110 family act as nucleotide exchange factors of Hsp70s. EMBO J 25(11):2519-28
8) Easton DP, et al.  (2000) The hsp110 and Grp1 70 stress proteins: newly recognized relatives of the Hsp70s. Cell Stress Chaperones 5(4):276-90
9) Trott A, et al.  (2005) The molecular chaperone Sse1 and the growth control protein kinase Sch9 collaborate to regulate protein kinase A activity in Saccharomyces cerevisiae. Genetics 170(3):1009-21
10) Liu XD, et al.  (1999) The yeast Hsp110 family member, Sse1, is an Hsp90 cochaperone. J Biol Chem 274(38):26654-60
11) Raviol H, et al.  (2006) Human and yeast Hsp110 chaperones exhibit functional differences. FEBS Lett 580(1):168-74