SSB1/YDL229W Summary Help

Standard Name SSB1
Systematic Name YDL229W
Alias YG101 1
Feature Type ORF, Verified
Description Cytoplasmic ATPase that is a ribosome-associated molecular chaperone; functions with J-protein partner Zuo1p; may be involved in folding of newly-made polypeptide chains; member of the HSP70 family; interacts with phosphatase subunit Reg1p; SSB1 has a paralog, SSB2, that arose from the whole genome duplication (2, 3, 4, 5, 6, 7, 8, 9 and see Summary Paragraph)
Name Description Stress-Seventy subfamily B
Chromosomal Location
ChrIV:44065 to 45906 | ORF Map | GBrowse
Gbrowse
Genetic position: -129 cM
Gene Ontology Annotations All SSB1 GO evidence and references
  View Computational GO annotations for SSB1
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Manually curated
High-throughput
Regulators 3 genes
Resources
Classical genetics
null
overexpression
Large-scale survey
null
Resources
1035 total interaction(s) for 623 unique genes/features.
Physical Interactions
  • Affinity Capture-MS: 938
  • Affinity Capture-RNA: 7
  • Affinity Capture-Western: 15
  • Co-fractionation: 1
  • Co-purification: 2
  • PCA: 5
  • Reconstituted Complex: 3

Genetic Interactions
  • Dosage Lethality: 2
  • Dosage Rescue: 16
  • Negative Genetic: 27
  • Phenotypic Enhancement: 3
  • Phenotypic Suppression: 1
  • Positive Genetic: 2
  • Synthetic Growth Defect: 10
  • Synthetic Lethality: 1
  • Synthetic Rescue: 2

Resources
Expression Summary
histogram
Resources
Length (a.a.) 613
Molecular Weight (Da) 66,601
Isoelectric Point (pI) 5.18
Localization
Phosphorylation PhosphoGRID | PhosphoPep Database
Structure
Homologs
sequence information
ChrIV:44065 to 45906 | ORF Map | GBrowse
SGD ORF map
Genetic position: -129 cM
Last Update Coordinates: 2011-02-03 | Sequence: 1996-07-31
Subfeature details
Relative
Coordinates
Chromosomal
Coordinates
Most Recent Updates
Coordinates Sequence
CDS 1..1842 44065..45906 2011-02-03 1996-07-31
Retrieve sequences
Analyze Sequence
S288C only
S288C vs. other species
S288C vs. other strains
Resources
External Links All Associated Seq | Entrez Gene | Entrez RefSeq Protein | MIPS | Search all NCBI (Entrez) | UniProtKB
Primary SGDIDS000002388
SUMMARY PARAGRAPH for SSB1

SSB1 and SSB2 encode chaperone proteins that are members of the S. cerevisiae SSB subfamily of cytosolic HSP70 proteins (10). 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 (reviewed in 11). S. cerevisiae has at least 9 cytosolic forms of HSP70 (SSA1, SSA2, SSA3, SSA4, SSB1, SSB2, SSE1, SSE2, SSZ1), 2 HSP70s which are found in the endoplasmic reticulum (KAR2, LHS1), and 3 mitochondrial HSP70 proteins (SSC1, SSQ1, ECM10). SSB1 and SSB2 are 99% identical to each other and 63% identical to SSA1-4, the main cytosolic subfamily of HSP70s (12). The main function of HSP70s is to serve as molecular chaperones, binding newly-translated proteins to assist in proper folding and prevent aggregation/misfolding (reviewed in 11 and 13). The chaperone activity of Ssb1p and Ssb2p is localized to the ribosome as part of the ribosome-associated complex (RAC; 14). RAC, which includes either Ssb1p or Ssb2p along with the Hsp70 protein Ssz1p and the DnaJ homolog Zuo1p, binds both the active ribosome and the associated nascent polypeptide chain (15).

Like all other Hsp70 proteins, Ssb1p and Ssb2p contain an N-terminal ATPase domain and a C-terminal peptide-binding domain (16). Unlike most HSP70 genes, SSB1 and SSB2 expression is repressed, as opposed to induced, upon heat shock (17). Instead, SSB transcription is coregulated with ribosomal protein genes (18). Double mutant strains null for both ssb1 and ssb2 are sensitive to cold and to translation-impairing drugs (17, 2). Overproduction of Ssb1p has been shown to cure cells propagating the prion form of Sup35p, [PSI+] (19, 20).

Last updated: 2006-02-07 Contact SGD

References cited on this page View Complete Literature Guide for SSB1
1) Ingolia TD, et al.  (1982) Saccharomyces cerevisiae contains a complex multigene family related to the major heat shock-inducible gene of Drosophila. Mol Cell Biol 2(11):1388-98
2) Nelson RJ, et al.  (1992) The translation machinery and 70 kd heat shock protein cooperate in protein synthesis. Cell 71(1):97-105
3) Shulga N, et al.  (1999) A nuclear export signal prevents Saccharomyces cerevisiae Hsp70 Ssb1p from stimulating nuclear localization signal-directed nuclear transport. J Biol Chem 274(23):16501-7
4) Craig EA, et al.  (1993) Heat shock proteins: molecular chaperones of protein biogenesis. Microbiol Rev 57(2):402-14
5) Lopez-Buesa P, et al.  (1998) The biochemical properties of the ATPase activity of a 70-kDa heat shock protein (Hsp70) are governed by the C-terminal domains. Proc Natl Acad Sci U S A 95(26):15253-8
6) de Nobel H, et al.  (2001) Parallel and comparative analysis of the proteome and transcriptome of sorbic acid-stressed Saccharomyces cerevisiae. Yeast 18(15):1413-28
7) Kim SY and Craig EA  (2005) Broad sensitivity of Saccharomyces cerevisiae lacking ribosome-associated chaperone ssb or zuo1 to cations, including aminoglycosides. Eukaryot Cell 4(1):82-9
8) Huang P, et al.  (2005) The Hsp70 Ssz1 modulates the function of the ribosome-associated J-protein Zuo1. Nat Struct Mol Biol 12(6):497-504
9) 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
10) Werner-Washburne M, et al.  (1987) Complex interactions among members of an essential subfamily of hsp70 genes in Saccharomyces cerevisiae. Mol Cell Biol 7(7):2568-77
11) Bukau B and Horwich AL  (1998) The Hsp70 and Hsp60 chaperone machines. Cell 92(3):351-66
12) Boorstein WR, et al.  (1994) Molecular evolution of the HSP70 multigene family. J Mol Evol 38(1):1-17
13) Becker J and Craig EA  (1994) Heat-shock proteins as molecular chaperones. Eur J Biochem 219(1-2):11-23
14) Pfund C, et al.  (1998) The molecular chaperone Ssb from Saccharomyces cerevisiae is a component of the ribosome-nascent chain complex. EMBO J 17(14):3981-9
15) Gautschi M, et al.  (2002) A functional chaperone triad on the yeast ribosome. Proc Natl Acad Sci U S A 99(7):4209-14
16) Pfund C, et al.  (2001) Divergent functional properties of the ribosome-associated molecular chaperone Ssb compared with other Hsp70s. Mol Biol Cell 12(12):3773-82
17) Craig EA and Jacobsen K  (1985) Mutations in cognate genes of Saccharomyces cerevisiae hsp70 result in reduced growth rates at low temperatures. Mol Cell Biol 5(12):3517-24
18) Lopez N, et al.  (1999) SSB, encoding a ribosome-associated chaperone, is coordinately regulated with ribosomal protein genes. J Bacteriol 181(10):3136-43
19) Chacinska A, et al.  (2001) Ssb1 chaperone is a [PSI+] prion-curing factor. Curr Genet 39(2):62-7
20) Kushnirov VV, et al.  (2000) Chaperones that cure yeast artificial [PSI+] and their prion-specific effects. Curr Biol 10(22):1443-6