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Protein

Ribosome-associated molecular chaperone SSB2

Gene

SSB2

Organism
Saccharomyces cerevisiae (strain ATCC 204508 / S288c) (Baker's yeast)
Status
Reviewed-Annotation score: Annotation score: 5 out of 5-Experimental evidence at protein leveli

Functioni

Ribosome-bound, Hsp70-type chaperone that assists in the cotranslational folding of newly synthesized proteins in the cytosol. Stimulates folding by interacting with nascent chains, binding to short, largely hydrophobic sequences exposed by unfolded proteins, thereby stabilizing longer, more slowly translated, and aggregation-prone nascent polypeptides and domains that cannot fold stably until fully synthesized. The Hsp70-protein substrate interaction depends on ATP-binding and on allosteric regulation between the NBD and the SBD. The ATP-bound state is characterized by a fast exchange rate of substrate (low affinity state), while in the ADP-bound state exchange is much slower (high affinity state). During the Hsp70 cycle, the chaperone switches between the ATP-bound state (open conformation) and the ADP-bound state (closed conformation) by major conformational rearrangements involving mainly the lid domain. Ssb cooperates with a specific Hsp40/Hsp70 co-chaperone termed the ribosome-associated complex (RAC), which stimulates the ATPase activity of the ribosome-associated pool of Ssbs and switches it to the high affinity substrate binding state. Hsp110 chaperone SSE1 and FES1 act as nucleotide exchange factors that cause substrate release.7 Publications

Miscellaneous

Present with 104000 molecules/cell in log phase SD medium.1 Publication

Catalytic activityi

ATP + H2O = ADP + phosphate.By similarity

Sites

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Binding sitei73ATPBy similarity1
Binding sitei342ATP; via amide nitrogenBy similarity1

Regions

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Nucleotide bindingi16 – 18ATPBy similarity3
Nucleotide bindingi205 – 207ATPBy similarity3
Nucleotide bindingi271 – 278ATPBy similarity8

GO - Molecular functioni

  • ATPase activity Source: SGD
  • ATP binding Source: UniProtKB-KW
  • unfolded protein binding Source: SGD

GO - Biological processi

  • 'de novo' cotranslational protein folding Source: SGD
  • cellular response to glucose starvation Source: SGD
  • cytoplasmic translation Source: SGD
  • regulation of translational fidelity Source: SGD
  • ribosomal subunit export from nucleus Source: SGD
  • rRNA processing Source: SGD
  • translational frameshifting Source: SGD

Keywordsi

Molecular functionChaperone, Hydrolase
Biological processProtein biosynthesis
LigandATP-binding, Nucleotide-binding

Enzyme and pathway databases

BioCyciYEAST:G3O-33215-MONOMER.

Names & Taxonomyi

Protein namesi
Recommended name:
Ribosome-associated molecular chaperone SSB21 Publication (EC:3.6.4.10)
Alternative name(s):
Heat shock protein SSB21 Publication
Hsp70 chaperone Ssb
Gene namesi
Name:SSB21 Publication
Synonyms:YG1031 Publication
Ordered Locus Names:YNL209WImported
ORF Names:N1333
OrganismiSaccharomyces cerevisiae (strain ATCC 204508 / S288c) (Baker's yeast)
Taxonomic identifieri559292 [NCBI]
Taxonomic lineageiEukaryotaFungiDikaryaAscomycotaSaccharomycotinaSaccharomycetesSaccharomycetalesSaccharomycetaceaeSaccharomyces
Proteomesi
  • UP000002311 Componenti: Chromosome XIV

Organism-specific databases

EuPathDBiFungiDB:YNL209W.
SGDiS000005153. SSB2.

Subcellular locationi

Keywords - Cellular componenti

Cytoplasm

PTM / Processingi

Molecule processing

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Initiator methionineiRemoved1 Publication
ChainiPRO_00000783902 – 613Ribosome-associated molecular chaperone SSB2Add BLAST612

Amino acid modifications

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Modified residuei2N-acetylalanine1 Publication1
Modified residuei47PhosphothreonineCombined sources1
Modified residuei431PhosphothreonineBy similarity1

Keywords - PTMi

Acetylation, Phosphoprotein

Proteomic databases

MaxQBiP40150.
PRIDEiP40150.
TopDownProteomicsiP40150.

2D gel databases

COMPLUYEAST-2DPAGEiP40150.

PTM databases

iPTMnetiP40150.

Expressioni

Inductioni

Expression decreases after heat shock or during growth to stationary phase (PubMed:6761581, PubMed:2651414). Up-regulated upon carbon upshift and down-regulated upon amino acid limitation in an HSF1-dependent manner (PubMed:10322015). Interacts with SSE1 (PubMed:16219770, PubMed:16221677). Interacts with FES1 (By similarity).By similarity5 Publications

Interactioni

Subunit structurei

Binds to ribosomes (PubMed:9670014, PubMed:1394434, PubMed:27917864). Binds close to the ribosomal tunnel exit via contacts with both ribosomal proteins RPL35, RPL39 and RPL19, and rRNA (By similarity). Directly interacts with nascent polypeptides. This interaction is dependent on the ribosome-associated complex (RAC) (PubMed:11929994, PubMed:23332755). Interacts with SSE1 (PubMed:23332755).By similarity5 Publications

Binary interactionsi

Show more details

GO - Molecular functioni

  • unfolded protein binding Source: SGD

Protein-protein interaction databases

BioGridi35627. 2073 interactors.
DIPiDIP-7126N.
IntActiP40150. 1320 interactors.
MINTiMINT-2737291.
STRINGi4932.YNL209W.

Structurei

3D structure databases

ProteinModelPortaliP40150.
SMRiP40150.
ModBaseiSearch...
MobiDBiSearch...

Family & Domainsi

Region

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Regioni2 – 391Nucleotide binding domain (NBD)By similarityAdd BLAST390
Regioni392 – 402Inter-domain linkerBy similarityAdd BLAST11
Regioni403 – 613Substrate binding domain (SBD)By similarityAdd BLAST211
Regioni516 – 612Lid domain (SBDalpha)By similarityAdd BLAST97
Regioni601 – 613Required for interaction with ribosomes1 PublicationAdd BLAST13

Motif

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Motifi428 – 430Contributes to ribosome binding1 Publication3
Motifi574 – 582Nuclear export signalBy similarity9

Sequence similaritiesi

Phylogenomic databases

GeneTreeiENSGT00890000140068.
HOGENOMiHOG000228135.
InParanoidiP40150.
KOiK03283.
OMAiDFSARHE.
OrthoDBiEOG092C1VPN.

Family and domain databases

Gene3Di1.20.1270.10. 1 hit.
2.60.34.10. 1 hit.
InterProiView protein in InterPro
IPR018181. Heat_shock_70_CS.
IPR029048. HSP70_C.
IPR029047. HSP70_peptide-bd.
IPR013126. Hsp_70_fam.
PfamiView protein in Pfam
PF00012. HSP70. 1 hit.
PRINTSiPR00301. HEATSHOCK70.
SUPFAMiSSF100920. SSF100920. 1 hit.
SSF100934. SSF100934. 1 hit.
PROSITEiView protein in PROSITE
PS00297. HSP70_1. 1 hit.
PS00329. HSP70_2. 1 hit.
PS01036. HSP70_3. 1 hit.

Sequencei

Sequence statusi: Complete.

Sequence processingi: The displayed sequence is further processed into a mature form.

P40150-1 [UniParc]FASTAAdd to basket

« Hide

        10         20         30         40         50
MAEGVFQGAI GIDLGTTYSC VATYESSVEI IANEQGNRVT PSFVAFTPQE
60 70 80 90 100
RLIGDAAKNQ AALNPRNTVF DAKRLIGRRF DDESVQKDMK TWPFKVIDVD
110 120 130 140 150
GNPVIEVQYL EETKTFSPQE ISAMVLTKMK EIAEAKIGKK VEKAVITVPA
160 170 180 190 200
YFNDAQRQAT KDAGAISGLN VLRIINEPTA AAIAYGLGAG KSEKERHVLI
210 220 230 240 250
FDLGGGTFDV SLLHIAGGVY TVKSTSGNTH LGGQDFDTNL LEHFKAEFKK
260 270 280 290 300
KTGLDISDDA RALRRLRTAA ERAKRTLSSV TQTTVEVDSL FDGEDFESSL
310 320 330 340 350
TRARFEDLNA ALFKSTLEPV EQVLKDAKIS KSQIDEVVLV GGSTRIPKVQ
360 370 380 390 400
KLLSDFFDGK QLEKSINPDE AVAYGAAVQG AILTGQSTSD ETKDLLLLDV
410 420 430 440 450
APLSLGVGMQ GDIFGIVVPR NTTVPTIKRR TFTTVSDNQT TVQFPVYQGE
460 470 480 490 500
RVNCKENTLL GEFDLKNIPM MPAGEPVLEA IFEVDANGIL KVTAVEKSTG
510 520 530 540 550
KSSNITISNA VGRLSSEEIE KMVNQAEEFK AADEAFAKKH EARQRLESYV
560 570 580 590 600
ASIEQTVTDP VLSSKLKRGS KSKIEAALSD ALAALQIEDP SADELRKAEV
610
GLKRVVTKAM SSR
Length:613
Mass (Da):66,595
Last modified:January 23, 2007 - v2
Checksum:iE1040A011346D953
GO

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
X78898 Genomic DNA. Translation: CAA55498.1.
Z71485 Genomic DNA. Translation: CAA96111.1.
M17586 Genomic DNA. Translation: AAA34693.1.
BK006947 Genomic DNA. Translation: DAA10347.1.
PIRiS50721.
RefSeqiNP_014190.1. NM_001183047.1.

Genome annotation databases

EnsemblFungiiYNL209W; YNL209W; YNL209W.
GeneIDi855512.
KEGGisce:YNL209W.

Similar proteinsi

Entry informationi

Entry nameiSSB2_YEAST
AccessioniPrimary (citable) accession number: P40150
Secondary accession number(s): D6W0Y1
Entry historyiIntegrated into UniProtKB/Swiss-Prot: February 1, 1995
Last sequence update: January 23, 2007
Last modified: September 27, 2017
This is version 159 of the entry and version 2 of the sequence. See complete history.
Entry statusiReviewed (UniProtKB/Swiss-Prot)
Annotation programFungal Protein Annotation Program

Miscellaneousi

Keywords - Technical termi

Complete proteome, Direct protein sequencing, Reference proteome

Documents

  1. SIMILARITY comments
    Index of protein domains and families
  2. Yeast
    Yeast (Saccharomyces cerevisiae): entries, gene names and cross-references to SGD
  3. Yeast chromosome XIV
    Yeast (Saccharomyces cerevisiae) chromosome XIV: entries and gene names