HSPA12A

Gap: The biochemical nucleotide behavior of HSPA12A remains unresolved at the boundary between divergent HSP70-family architecture and non-chaperone adaptor function. Current evidence argues against assigning canonical ATP-dependent protein-folding chaperone activity, but direct ATP binding, ATP hydrolysis rate, and possible nucleotide-regulated conformational switching have not been experimentally defined.

NARROWING BIOLOGYCURATION RESIDUAL_SUBGAP

What is known: The review treats HSPA12A as a SorLA/SORL1-tail binding adaptor-like protein, not as a canonical HSP70 folding chaperone. The gap is whether the retained divergent nucleotide-binding domain has measurable ATP/ADP binding or hydrolysis that regulates adaptor interactions, not whether HSPA12A should be annotated to ATP-dependent folding chaperone activity.

Significance: Resolving this would determine whether ATP-binding or ATPase-related annotations are appropriate as narrow mechanistic qualifiers, while avoiding over-propagation of canonical HSP70 chaperone terms from family membership.

What would resolve it: Purified HSPA12A ATP/ADP binding measurements, basal and cofactor-stimulated ATPase assays, and nucleotide-dependent SorLA-binding/conformation assays should be compared directly with canonical HSP70 controls.

Provenance (the field's own admissions):

• "Current evidence in retrieved primary literature is insufficient to support canonical HSP70 chaperone/protein-folding activity for HSPA12A." — file:human/HSPA12A/HSPA12A-deep-research-falcon.md
• "ATP hydrolysis rate unknown | No published ATPase kinetics for HSPA12A" — file:human/HSPA12A/HSPA12A-hypotheses/hsp70-folding-machinery-check/openscientist.md
• "ATP binding unconfirmed experimentally | Only IEA annotation exists" — file:human/HSPA12A/HSPA12A-hypotheses/hsp70-folding-machinery-check/openscientist.md

Gap: The endogenous mechanism by which HSPA12A changes SorLA/SORL1 internalization and trafficking remains underdefined. SorLA-tail binding and delayed internalization are supported, but it is not clear whether HSPA12A acts by competing with GGA/AP adaptor machinery, by altering vesicle identity, by nucleotide-regulated tail binding, or by another receptor-scaffold mechanism.

OPEN BIOLOGYONTOLOGYCURATION BP_DARK

What is known: The review supports negative regulation of receptor internalization for SorLA and proposes a more specific sorting-receptor cytoplasmic-tail binding term. The gap is the mechanistic bridge from tail binding to trafficking outcome, especially in endogenous neuronal or glial systems.

Significance: This gap determines how specific HSPA12A's process annotations should be, and whether a new molecular-function term should represent simple receptor-tail binding, cargo-adaptor competition, or a more specific trafficking-adaptor activity.

What would resolve it: Endogenous knock-in/co-IP or proximity-labeling in neuronal and glial models, SorLA-tail motif mutants, GGA/AP adaptor competition assays, and vesicle identity markers would define the direct trafficking mechanism.

Provenance (the field's own admissions):

• "The D47D48 motif overlaps a reported GGA2 binding site, raising a mechanistic possibility of adaptor competition" — file:human/HSPA12A/HSPA12A-deep-research-falcon.md
• "Many trafficking/localization effects were measured in HEK293 transfectants, and localization includes tagged HSPA12A constructs; these are strong for mechanistic hypotheses but should be curated with appropriate evidence codes and caution" — file:human/HSPA12A/HSPA12A-deep-research-falcon.md
• "direct effects on APP processing/amyloid output were not required to support the GO-relevant trafficking statements" — file:human/HSPA12A/HSPA12A-deep-research-falcon.md

Gap: HSPA12A's broader adaptor/regulatory interaction network outside SorLA is not settled. Disease-context studies report signaling or scaffold-like effects, but it is unclear which partners are direct endogenous HSPA12A clients and which phenotypes are downstream consequences of stress, metabolic, or tissue-specific contexts.

OPEN BIOLOGYCURATION MF_DARK

What is known: The review keeps the core function narrow around SorLA cytosolic-tail binding and receptor internalization. It does not convert PCNA, Smurf1/HIF1alpha, PGC-1alpha/AOAH, PKM2, or other disease-context reports into broad core proteostasis or signaling annotations.

Significance: A resolved endogenous interaction network would show whether HSPA12A is a mostly SorLA-selective trafficking adaptor or a broader regulatory scaffold with additional curated molecular functions and biological-process roles.

What would resolve it: AP-MS/BioID/TurboID in relevant primary cell types, endogenous rescue with interaction-defective HSPA12A mutants, and direct partner-binding assays should separate direct adaptor interactions from downstream disease phenotypes.

Provenance (the field's own admissions):

• "Complete interaction network | SORL1 adapter function established; other partners unknown" — file:human/HSPA12A/HSPA12A-hypotheses/hsp70-folding-machinery-check/openscientist.md
• "Several published phenotypes associated with HSPA12A — cardioprotection during ischemia/reperfusion, attenuation of septic liver injury, neuroprotection after seizures, roles in NASH and diabetes — are downstream consequences of its adapter/regulatory functions, not evidence of chaperone activity." — file:human/HSPA12A/HSPA12A-hypotheses/hsp70-folding-machinery-check/openscientist.md
• "Additional adapter/regulatory functions may exist" — file:human/HSPA12A/HSPA12A-hypotheses/hsp70-folding-machinery-check/openscientist.md