Falcon deep research report for human HSPA12A
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HSPA12A supports a narrow SorLA/SORL1 trafficking mechanism rather than established canonical HSP70 folding activity.
"Current evidence in retrieved primary literature is insufficient to support canonical HSP70 chaperone/protein-folding activity for HSPA12A."
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HSPA12A specifically binds the SorLA cytosolic tail with nucleotide sensitivity.
"HSPA12A was identified as a **specific SorLA cytosolic-tail interactor**; Y2H recovered C-terminal HSPA12A clones, GST-HSPA12A pulled down full-length SorLA, and binding mapped to SorLA cytosolic acidic clusters including E34-D38 and D47D48. HSPA12B was negative in Y2H, arguing against paralog transfer."
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HSPA12A delays SorLA internalization.
"HSPA12A **delays SorLA internalization/endocytosis**: surface SorLA staining persisted longer in HSPA12A-expressing cells, and labeled SorLA accumulated in HSPA12A-positive vesicles."
Two Hsp70 family members expressed in atherosclerotic lesions.
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Han et al. place HSPA12A/HSPA12B as distant HSP70-family members with atypical ATPase-domain similarity.
"Both genes appear to contain an atypical Hsp70 ATPase domain. The BLAST search also revealed that both genes were more similar to primitive eukaryote and prokaryote than mammalian Hsp70s, making these two genes distant members of the mammalian Hsp70 family."
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The original HSPA12A/HSPA12B characterization cautions against assuming canonical HSP70 function from domain placement alone.
"Despite HspA12A and HspA12B localization to macrophages in lesions and their placement into the Hsp70 family by computer algorithms, we cannot be certain that they share any of the functions of Hsp70s."
Heat-Shock protein A12A is a novel PCNA-binding protein and promotes hepatocellular carcinoma growth.
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Cheng et al. report a disease-context PCNA interaction, not canonical HSP70 folding or ATPase activity.
"HSPA12A directly binds to PCNA and promotes its trimerization, which is an essential functional conformation of PCNA for carcinogenesis."
Manual transfer of experimentally-verified manual GO annotation data to orthologs by curator judgment of sequence similarity
Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary mapping, accompanied by conservative changes to GO terms applied by UniProt
Large-scale proteomics and phosphoproteomics of urinary exosomes.
HSPA12A targets the cytoplasmic domain and affects the trafficking of the Amyloid Precursor Protein receptor SorLA.
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HSPA12A selectively binds the cytosolic tail of SorLA in an ADP/ATP-dependent manner
"We have identified HSPA12A as a new adaptor protein that, among Vps10p-D receptors, selectively binds to SorLA in an ADP/ATP dependent manner."
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SorLA is the first described substrate of HSPA12A in this study
"This is the first described substrate of HSPA12A."
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HSPA12A lowers SorLA internalization and alters its trafficking
"We also observed that the endocytic capacity of SorLA was lowered by HSPA12A expression (Fig. 7). Together, these data clearly show HSPA12A has cellular effects on SorLA localisation and trafficking."
A reference map of the human binary protein interactome.
Dual proteome-scale networks reveal cell-specific remodeling of the human interactome.
Multimodal cell maps as a foundation for structural and functional genomics.
UniProt entry for HSPA12A (O43301)
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UniProt curates HSPA12A as an adapter protein for SORL1 and not SORT1
"CC -!- FUNCTION: Adapter protein for SORL1, but not SORT1."
Curator notes on HSPA12A PN context and conservative GO review
OpenScientist hypothesis run: HSPA12A HSP70 folding-machinery check
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Confirms HSPA12A is a divergent non-canonical HSP70 for which GO:0140662 (ATP-dependent protein folding chaperone) should not be assigned - all three PROSITE HSP70 signatures, the substrate-binding domain, the interdomain linker, and the C-terminal EEVD are absent. Corroborates the PN workbook InterPro domain deficit (only the root ATPase fold is shared with canonical HSPA8).
"lacks the molecular machinery required for canonical ATP-dependent protein folding chaperone activity"