GO_REF:0000033

Annotation inferences using phylogenetic trees

GO_REF:0000043

Gene Ontology annotation based on UniProtKB/Swiss-Prot keyword mapping

GO_REF:0000117

Electronic Gene Ontology annotations created by ARBA machine learning models

GO_REF:0000120

Combined Automated Annotation using Multiple IEA Methods

PMID:10745074

Cytosolic Hsp70s are involved in the transport of aminopeptidase 1 from the cytoplasm into the vacuole.

The cached abstract establishes a cytoplasmic Ssa-family context but reports its detailed localization and transport results for Ssa1/2 rather than Ssa3 specifically.

"the constitutively expressed members of the yeast cytoplasmic Ssa subfamily, Ssa1/2p, are involved in the transport of the vacuolar hydrolase aminopeptidase 1 from the cytoplasm into the vacuole."

PMID:11805837

Systematic identification of protein complexes in Saccharomyces cerevisiae by mass spectrometry.

The source reports high-throughput mass-spectrometric identification of protein complexes rather than targeted binary tests for every edge.

"Here we report, using the budding yeast Saccharomyces cerevisiae as a test case, an example of this approach, which we term high-throughput mass spectrometric protein complex identification (HMS-PCI)."

PMID:16554755

Global landscape of protein complexes in the yeast Saccharomyces cerevisiae.

The interaction map is based on tandem affinity purification and mass spectrometry of thousands of tagged yeast proteins.

"We used tandem affinity purification to process 4,562 different tagged proteins of the yeast Saccharomyces cerevisiae. Each preparation was analysed by both matrix-assisted laser desorption/ionization-time of flight mass spectrometry and liquid chromatography tandem mass spectrometry"

PMID:19536198

An atlas of chaperone-protein interactions in Saccharomyces cerevisiae: implications to protein folding pathways in the cell.

The chaperone-atlas associations are indirect TAP-tag complex interactions rather than proof of direct binary binding.

"It should be emphasized that the interactions presented are indirect TAP-tag based interactions and not direct binary interactions."

PMID:24855027

Life-span extension by a metacaspase in the yeast Saccharomyces cerevisiae.

PMID:27107014

An inter-species protein-protein interaction network across vast evolutionary distance.

PMID:31454312

The role of structural pleiotropy and regulatory evolution in the retention of heteromers of paralogs.

The study finds that heteromerization is frequent among duplicated yeast homomers and correlates with paralog functional similarity.

"Using yeast as a model, we find that heteromerization is frequent among duplicated homomers and correlates with functional similarity between paralogs."

PMID:3302682

Complex interactions among members of an essential subfamily of hsp70 genes in Saccharomyces cerevisiae.

SSA3 is heat inducible and can provide essential Ssa-family function when expressed from the constitutive SSA2 promoter.

"Nevertheless, an intact copy of SSA3 regulated by the constitutive SSA2 promoter was capable of rescuing a ssa1 ssa2 ssa4 strain."

PMID:8754838

Functional interaction of cytosolic hsp70 and a DnaJ-related protein, Ydj1p, in protein translocation in vivo.

SSA-family Hsp70 and Ydj1 cooperate in precursor protein translocation in vivo, supporting post-translational import rather than SRP-dependent cotranslational targeting.

"These results are consistent with SSA proteins and Ydj1p acting together in the translocation process."

PMID:9789005

Folding in vivo of a newly translated yeast cytosolic enzyme is mediated by the SSA class of cytosolic yeast Hsp70 proteins.

SSA-family cytosolic Hsp70s assist ATP-dependent folding of newly translated cytosolic proteins in vivo.

"These findings indicate that, in vivo, the Hsp70 system assists in folding at least some newly translated cytosolic enzymes"

file:yeast/SSA3/SSA3-deep-research-falcon.md

Falcon deep research report on SSA3

SSA3 encodes Ssa3, one of the four cytosolic Hsp70-Ssa proteins (Ssa1-Ssa4) in budding yeast and the stress/heat-inducible branch of the family, in contrast to the constitutively expressed Ssa1/Ssa2.

"SSA3 is repeatedly described as a **heat/stress-inducible** cytosolic Hsp70, in contrast to **SSA1/SSA2**, which are constitutively expressed."
Ssa3 is a cytosolic ATP-dependent protein chaperone that assists folding/refolding and limits aggregation of stress-denatured proteins as part of the major cytosolic Hsp70 system.

"SSA3 encodes a **cytosolic ATP-dependent protein chaperone** that participates in proteostasis by assisting folding/refolding and limiting aggregation of stress-denatured proteins."
Hsp70/Ssa chaperones are ATP-dependent: they bind exposed hydrophobic segments of non-native proteins to prevent aggregation and promote folding/refolding and quality control.

"Hsp70/Ssa chaperones are **ATP-dependent**. They bind exposed hydrophobic segments of non-native proteins to prevent aggregation and promote productive folding/refolding and quality control."
Hsp70 architecture comprises an N-terminal nucleotide-binding/ATPase domain (NBD) and a substrate-binding domain (SBD) with a helical lid; ATP binding and hydrolysis drive switching between substrate-affinity states, with Hsp40 J-proteins stimulating ATP hydrolysis and nucleotide-exchange factors resetting the cycle.

"ATP binding and hydrolysis drive switching between low-affinity/high-exchange and high-affinity/slow-exchange substrate states; co-chaperones (notably J-domain proteins/Hsp40s) stimulate ATP hydrolysis and nucleotide-exchange factors reset the cycle."
Ssa proteins function with Hsp40 (J-domain) co-chaperones and Hsp110 nucleotide-exchange factors and promote folding, translocation, degradation, and refolding of denatured substrates.

"Ssa proteins promote folding, translocation, degradation, and refolding of denatured substrates"
SSA3 is a canonical Hsf1-regulated heat shock response gene with extremely low basal expression that is rapidly induced by heat shock/stress, unlike the constitutive SSA1/SSA2.

"SSA3 has extremely low basal expression under optimal conditions but is rapidly induced by heat shock/stress"
SSA3 heat inducibility was mapped to two overlapping heat shock elements (HSEs) centered ~-156 bp upstream that were necessary and sufficient for heat induction; an SSA3-lacZ fusion showed very low basal activity (~4 Miller units at 23C) and strong induction within 30 minutes of heat shock.

"A foundational promoter-dissection study mapped SSA3 heat inducibility to **two overlapping HSEs centered ~−156 bp upstream** of the transcribed region; these sequences were **necessary and sufficient** for heat induction."
Ssa3 is consistently treated as a cytosolic Hsp70 of the Ssa family (in contrast to compartment-specific Hsp70s such as ER BiP/Kar2), with functions in the cytosol/nucleus proteostasis network.

"SSA3 is consistently treated as a **cytosolic** Hsp70 of the Ssa family"
Although the Ssa paralogs are partly redundant (yeast requires at least one Ssa for growth and paralogs can substantially compensate), Ssa3 shows measurable functional specialization, including being reported as the most proficient isoform for [PSI+] prion propagation/maintenance.

"Ssa3 was reported as the most proficient isoform for [PSI+] propagation/maintenance"

file:interpro/panther/PTHR19375/PTHR19375-paint.tsv

Current PANTHER PTHR19375 PAINT annotation snapshot

PTN002500132 currently carries nucleus and cytosol IBD assertions but no plasma-membrane assertion, showing that the pinned 2025 GOA transfer is stale.

file:yeast/SSA3/SSA3-hypotheses/existing-go-0005886-keep-as-non-core/openscientist.md

OpenScientist review of the SSA3 plasma-membrane IBA annotation

The plasma-membrane IBA lacks SSA3-specific experimental support and appears to be a family-level propagation; the report's live QuickGO absence claim conflicts with the pinned GOA snapshot and is not relied upon.

"The plasma-membrane assignment is a **phylogenetic (IBA) inference only**, carried on GO_REF:0000033, with no yeast-specific experimental support for Ssa3."