A0A8B8L1Z3

UniProt ID: A0A8B8L1Z3
Organism: Abrus precatorius
Review Status: DRAFT
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Gene Description

A0A8B8L1Z3 is a 474-amino-acid J-domain protein (JDP/Hsp40 family) from Abrus precatorius (Indian licorice). It contains a single DnaJ domain (residues 70-135, PF00226) with the conserved HPD motif required for allosteric activation of Hsp70 ATPase activity. The protein has extensive intrinsically disordered regions (residues 138-196 and 312-408) with proline-rich and basic/acidic compositional biases, an architecture more typical of cytoplasmic or nuclear J-domain proteins than ER-resident chaperones. It lacks a signal peptide, transmembrane domain, and ER-retention motif (KDEL/HDEL). The InterPro classification IPR053052 (Imprinting Balance Regulator) suggests homology to nuclear/cytoplasmic regulatory proteins. Based on its DnaJ domain, the protein is predicted to function as a cochaperone that recruits client proteins to Hsp70 and stimulates Hsp70 ATPase activity, supporting protein folding and proteostasis. No experimental characterization has been reported.

Core Functions

A0A8B8L1Z3 is predicted to function as a J-domain cochaperone based on its DnaJ domain (PF00226, IPR001623) at residues 70-135. J-domain proteins recruit client substrates to Hsp70 chaperones and stimulate Hsp70 ATPase activity via the conserved HPD motif. GO:0044183 (protein folding chaperone) is used following the annotation precedent for sHSP/DnaJ family proteins in Swiss-Prot; GO:0051082 (unfolded protein binding) is obsolete. The exact client specificity is unknown. The protein's extensive disordered regions and lack of ER-targeting signals suggest it operates in the cytoplasm or nucleus rather than the ER lumen. Confidence is low as no experimental evidence exists and the protein has PE level 4 (predicted existence only).

Molecular Function:
protein folding chaperone
Directly Involved In:
protein folding
Cellular Locations:
cytoplasm
Supporting Evidence:
  • file:ABRPR/A0A8B8L1Z3/A0A8B8L1Z3-deep-research-falcon.md
    LOC113860185 is best annotated as a J-domain (DnaJ-domain) protein and likely acts as an Hsp40/Hsp70 cochaperone that supports proteostasis and stress adaptation in Abrus precatorius

References

PMID:31775284
Detection of Abrin-Like and Prepropulchellin-Like Toxin Genes and Transcripts Using Whole Genome Sequencing and Full-Length Transcript Sequencing of Abrus precatorius

Suggested Questions for Experts

Q: What are the specific Hsp70 partner(s) for this J-domain protein in A. precatorius, and does the charged residue variation near its Hsp70-binding face create specificity for a particular Hsp70 paralog?

Q: Does the IPR053052 (Imprinting Balance Regulator) classification indicate a role in epigenetic regulation or chromatin remodeling rather than general protein folding?

Q: Is this protein expressed in specific tissues or developmental stages of A. precatorius, particularly under stress conditions?

Suggested Experiments

Experiment: Heterologously express and purify A0A8B8L1Z3, then test for stimulation of Hsp70 ATPase activity using a malachite green phosphate release assay. Include HPD motif mutants (H->Q) as negative controls. Test with both plant and E. coli DnaK/Hsp70 proteins to assess partner specificity.

Hypothesis: A0A8B8L1Z3 functions as an Hsp70 cochaperone that stimulates Hsp70 ATPase activity via its J-domain.

Type: biochemical assay

Experiment: Express A0A8B8L1Z3 with a C-terminal GFP tag in Nicotiana benthamiana leaves via Agrobacterium-mediated transient expression. Image by confocal microscopy with ER (mCherry-HDEL) and nuclear (DAPI) markers to determine subcellular localization.

Hypothesis: A0A8B8L1Z3 localizes to the cytoplasm or nucleus, not the ER.

Type: fluorescence microscopy

External Prediction Reviews

These computational predictions are reviewed separately from the GOA annotation set used for this review. The assessments below are from this project and do not constitute official GO annotations or endorsement by GO/UniProt. They are not included in the existing annotation review above.

ProtNLM2 External predictions

View prediction review YAML · A0A8B8L1Z3-protnlm-predictions-review.yaml · Review status: COMPLETE

The J-domain protein has insufficient evidence for localization to the endoplasmic reticulum.

Source documents: genes/ABRPR/A0A8B8L1Z3/A0A8B8L1Z3-uniprot.txt · genes/ABRPR/A0A8B8L1Z3/A0A8B8L1Z3-goa.tsv

Review score: 2 = concordant with evidence; 1 = uncertain; 0 = discordant with evidence. This is an assessment score, not a model probability.

GO:0005783 endoplasmic reticulum GO_CC
UNC — Uncertain Review score: 1/2
Prediction method: ProtNLM2 · Version: UniProt 2024_06 pilot
Review rationale: The sequence record identifies a J-domain at residues 70–135 in a 474-residue protein. This supports membership in a chaperone-related protein family but does not distinguish ER-localized proteins from J-domain proteins in other compartments. No ER localization annotation, diagnostic ER-targeting feature, or localization study is available in the inspected sources. The absence of an annotated signal peptide does not exclude association with the cytoplasmic face of the ER, so this localization remains uncertain.
Supporting Evidence:

Deep Research

Falcon

(A0A8B8L1Z3-deep-research-falcon.md)

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