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.
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?
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
The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.
You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.
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LOC113860185 (UniProt: A0A8B8L1Z3) encodes an uncharacterized protein from Abrus precatorius (Indian licorice), annotated in UniProt and NCBI with a canonical DnaJ (J-domain, Pfam: PF00226, IPR001623) domain, which unambiguously categorizes it as a member of the J-domain protein (JDP/Hsp40) superfamily. DnaJ domain-containing proteins are ubiquitous molecular cochaperones that interact with Hsp70 chaperones to drive diverse tasks in the maintenance of proteostasis and cellular stress response (zhang2023jdomainproteinchaperone pages 1-3, marszalek2024jdomainproteinsfrom pages 1-3, zhang2023jdomainproteinchaperone pages 3-4).
While no published experimental studies or functional reports specifically address LOC113860185 or its homologs in Abrus precatorius or related legumes as of 2023–2024, a robust body of recent reviews and mechanistic research has clarified DnaJ protein roles and mechanisms across eukaryotes, including in plants and crops. Advances in structural biology have elucidated that:
- DnaJ domain proteins bind and allosterically activate Hsp70 ATPase function via their highly conserved HPD motif.
- JDPs drive substrate recruitment to Hsp70, facilitate polypeptide folding, and play central roles in protein quality control, anti-aggregation, and stress resilience (liu2020structuralandfunctional pages 1-2, zhang2023jdomainproteinchaperone pages 1-3, zhang2023jdomainproteinchaperone pages 3-4, tomiczek2020twostepmechanismof pages 1-3).
- In plant systems, including legumes, DnaJ proteins can dynamically shuttle to different cellular or organellar compartments and participate in adaptive responses to environmental and biotic stresses (ku2022therelocalizationof pages 8-9, krupinska2020genomecommunicationin pages 1-2, krupinska2020genomecommunicationin pages 4-5).
See summary table for detailed mechanism and role breakdown.
| Primary Molecular Function | Mechanism of Action | Cellular Localization | Associated Pathways / Biological Processes | Key Citation / Reference |
|---|---|---|---|---|
| Hsp70 cochaperone / client recruitment factor | J-domain proteins (JDPs/Hsp40s) bind ATP-bound Hsp70 and help recruit selected client proteins, forming a transient JDP-Hsp70-client complex that initiates the chaperone cycle | Broadly distributed across cellular compartments and organisms; specific JDPs target distinct subcellular sites depending on additional domains | Core proteostasis, de novo folding, trafficking, complex assembly/disassembly, stress protection | (zhang2023jdomainproteinchaperone pages 1-3, zhang2023jdomainproteinchaperone pages 3-4) |
| ATPase activator of Hsp70 | The conserved J-domain docks at the Hsp70 NBD/interdomain linker/SBDβ interface and stimulates ATP hydrolysis, coupling client loading to stable client capture | Same compartment as partner Hsp70; localization is dictated by JDP architecture and targeting modules | Hsp70 cycle, protein quality control, substrate capture and release | (zhang2023jdomainproteinchaperone pages 3-4, tomiczek2020twostepmechanismof pages 1-3) |
| Canonical DnaJ/J-domain structural module | The J-domain is ~70 aa with four helices; helices II and III form a key interaction surface, and the domain corresponds to PF00226, the same Pfam assigned to LOC113860185 | Present within diverse JDP architectures; may occur N-terminally or elsewhere in class C proteins | Conserved structural basis for Hsp70 engagement across bacteria and eukaryotes | (zhang2023jdomainproteinchaperone pages 3-4, marszalek2024jdomainproteinsfrom pages 1-3) |
| HPD motif-mediated allosteric trigger | The invariant His-Pro-Asp (HPD) motif between helices II and III is essential for ATPase stimulation; the aspartate perturbs an Hsp70 intramolecular contact network to promote the allosteric transition leading to ATP hydrolysis | At the transient Hsp70-JDP binding interface | Allosteric control of chaperone action, substrate trapping, conformational cycling | (zhang2023jdomainproteinchaperone pages 3-4, tomiczek2020twostepmechanismof pages 1-3) |
| Protein folding and anti-aggregation factor | Iterative Hsp70/JDP cycles enable holding, unfolding/refolding, prevention of aggregation, disaggregation support, and triage of damaged proteins for degradation | Cytosol, organelles, membranes, and other compartment-specific proteostasis sites | Folding of nascent/misfolded proteins, aggregate control, stress recovery, proteome maintenance | (liu2020structuralandfunctional pages 1-2, zhang2023jdomainproteinchaperone pages 1-3, liu2020structuralandfunctional pages 4-5) |
| Client specificity determinant | Sequence variation, especially charged residues near the Hsp70-binding face of the J-domain, creates discriminatory electrostatic signatures that bias pairing with particular Hsp70 paralogs | Depends on the specialized JDP-Hsp70 pair and their compartment | Functional specialization of parallel chaperone circuits | (zhang2023jdomainproteinchaperone pages 6-8, tomiczek2020twostepmechanismof pages 1-3) |
| Organelle/membrane targeting scaffold | Regions outside the J-domain regulate client choice, partner assembly, and targeting of JDP-Hsp70 machineries to distinct cellular sites | Cytosol, mitochondria, ER, ribosome-associated complexes, membranes, nucleus/plastids in some plant proteins | Protein import, co-translational folding, compartment-specific proteostasis, signaling-linked relocalization | (zhang2023jdomainproteinchaperone pages 3-4, marszalek2024jdomainproteinsfrom pages 3-4, ku2022therelocalizationof pages 8-9, krupinska2020genomecommunicationin pages 4-5) |
| Plant stress-associated chaperone regulator | In plants, DnaJ-related proteins can relocalize among compartments and include organelle/nucleus-associated forms; plant J-like and DnaJ-like proteins participate in stress adaptation and organelle communication | Plasma membrane, chloroplast/plastid, nucleus, mitochondria, and other stress-responsive compartments | Abiotic/biotic stress responses, chloroplast development, retrograde/organelle-nucleus communication | (ku2022therelocalizationof pages 8-9, krupinska2020genomecommunicationin pages 1-2, krupinska2020genomecommunicationin pages 4-5) |
| Functional inference for Abrus precatorius LOC113860185 | Because LOC113860185 is an uncharacterized Abrus precatorius protein whose defining annotation is a DnaJ domain (PF00226), the strongest evidence-based inference is that it acts as a JDP/Hsp40-like cochaperone rather than an enzyme with a defined catalytic substrate | Exact localization unknown; likely inferable only after full-length sequence analysis or experiment, but expected to act where its partner Hsp70 and client proteins reside | Protein homeostasis / chaperone-mediated quality control; no direct pathway assignment yet for this specific Abrus protein | (zhang2023jdomainproteinchaperone pages 1-3, marszalek2024jdomainproteinsfrom pages 1-3, zhang2023jdomainproteinchaperone pages 3-4) |
Table: This table summarizes the core functional annotation of DnaJ domain-containing proteins/J-domain proteins based on the gathered evidence, emphasizing mechanism, localization, and biological roles. It is useful for inferring the likely function of the uncharacterized Abrus precatorius protein LOC113860185 from its conserved DnaJ domain.
Though no direct applications or biotechnological interventions targeting LOC113860185 or closely related plant DnaJ proteins in Abrus precatorius or economically relevant legumes are documented to date, there is increasing recognition in the last five years of the potential for engineered DnaJ proteins to enhance plant stress tolerance (abiotic and biotic), protein quality control, and crop yield stability. In model plants and crops, manipulation of DnaJ gene expression or domain structure is under research as a tool to bolster stress resistance—important for agricultural biotechnology, though no field application for Abrus precatorius is yet reported (ku2022therelocalizationof pages 8-9, krupinska2020genomecommunicationin pages 1-2).
Consensus from authoritative reviews is that the primary function of the DnaJ domain protein family is as cochaperones to Hsp70s, providing substrate specificity, enhancing ATPase activity, preventing and resolving toxic protein aggregates, and safeguarding protein homeostasis under both normal and stress-induced conditions (zhang2023jdomainproteinchaperone pages 1-3, zhang2023jdomainproteinchaperone pages 3-4, marszalek2024jdomainproteinsfrom pages 3-4, tomiczek2020twostepmechanismof pages 1-3). The J-domain architecture and the HPD motif are highly conserved and central to this role. In plants, DnaJ family proteins further mediate subcellular trafficking, stress response signaling, and organelle-nucleus communication, supporting a complex, compartmentalized proteostasis network (ku2022therelocalizationof pages 8-9, krupinska2020genomecommunicationin pages 1-2, krupinska2020genomecommunicationin pages 4-5).
In summary, LOC113860185 (A0A8B8L1Z3) 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. Its exact function, partners, and localization await experimental confirmation, but all evidence supports a canonical role in protein folding, anti-aggregation, and potential stress signaling or adaptation—mirroring DnaJ domain functions throughout plants and eukaryotes.
References
(zhang2023jdomainproteinchaperone pages 1-3): Ruobing Zhang, Duccio Malinverni, Douglas M. Cyr, Paolo De Los Rios, and Nadinath B. Nillegoda. J-domain protein chaperone circuits in proteostasis and disease. Jan 2023. URL: https://doi.org/10.1016/j.tcb.2022.05.004, doi:10.1016/j.tcb.2022.05.004. This article has 64 citations and is from a domain leading peer-reviewed journal.
(marszalek2024jdomainproteinsfrom pages 1-3): Jaroslaw Marszalek, Paolo De Los Rios, Douglas Cyr, Matthias P. Mayer, Vasista Adupa, Claes Andréasson, Gregory L. Blatch, Janice E.A. Braun, Jeffrey L. Brodsky, Bernd Bukau, J. Paul Chapple, Charlotte Conz, Sébastien Dementin, Pierre Genevaux, Olivier Genest, Pierre Goloubinoff, Jason Gestwicki, Colin M. Hammond, Justin K. Hines, Koji Ishikawa, Lukasz A. Joachimiak, Janine Kirstein, Krzysztof Liberek, Dejana Mokranjac, Nadinath Nillegoda, Carlos H.I. Ramos, Mathieu Rebeaud, David Ron, Sabine Rospert, Chandan Sahi, Reut Shalgi, Bartlomiej Tomiczek, Ryo Ushioda, Elizaveta Ustyantseva, Yihong Ye, Maciej Zylicz, and Harm H. Kampinga. J-domain proteins: from molecular mechanisms to diseases. Feb 2024. URL: https://doi.org/10.1016/j.cstres.2023.12.002, doi:10.1016/j.cstres.2023.12.002. This article has 25 citations and is from a peer-reviewed journal.
(zhang2023jdomainproteinchaperone pages 3-4): Ruobing Zhang, Duccio Malinverni, Douglas M. Cyr, Paolo De Los Rios, and Nadinath B. Nillegoda. J-domain protein chaperone circuits in proteostasis and disease. Jan 2023. URL: https://doi.org/10.1016/j.tcb.2022.05.004, doi:10.1016/j.tcb.2022.05.004. This article has 64 citations and is from a domain leading peer-reviewed journal.
(liu2020structuralandfunctional pages 1-2): Qinglian Liu, Ce Liang, and Lei Zhou. Structural and functional analysis of the hsp70/hsp40 chaperone system. Protein Science, 29:378-390, Feb 2020. URL: https://doi.org/10.1002/pro.3725, doi:10.1002/pro.3725. This article has 159 citations and is from a peer-reviewed journal.
(tomiczek2020twostepmechanismof pages 1-3): Bartlomiej Tomiczek, Wojciech Delewski, Łukasz Nierzwicki, Milena Stolarska, Igor Grochowina, Brenda Schilke, Rafał Dutkiewicz, Marta A. Uzarska, Szymon J. Ciesielski, Jacek Czub, and Jaroslaw Marszalek. Two-step mechanism of j-domain action in driving hsp70 function. PLoS Computational Biology, Jan 2020. URL: https://doi.org/10.1101/2020.01.13.901538, doi:10.1101/2020.01.13.901538. This article has 41 citations and is from a highest quality peer-reviewed journal.
(ku2022therelocalizationof pages 8-9): Yee-Shan Ku, Sau-Shan Cheng, Ming-Yan Cheung, Cheuk-Hin Law, and Hon-Ming Lam. The re-localization of proteins to or away from membranes as an effective strategy for regulating stress tolerance in plants. Membranes, 12:1261, Dec 2022. URL: https://doi.org/10.3390/membranes12121261, doi:10.3390/membranes12121261. This article has 12 citations.
(krupinska2020genomecommunicationin pages 1-2): Karin Krupinska, Nicolás E. Blanco, Svenja Oetke, and Michela Zottini. Genome communication in plants mediated by organelle–nucleus-located proteins. Philosophical Transactions of the Royal Society B: Biological Sciences, 375:20190397, May 2020. URL: https://doi.org/10.1098/rstb.2019.0397, doi:10.1098/rstb.2019.0397. This article has 54 citations and is from a domain leading peer-reviewed journal.
(krupinska2020genomecommunicationin pages 4-5): Karin Krupinska, Nicolás E. Blanco, Svenja Oetke, and Michela Zottini. Genome communication in plants mediated by organelle–nucleus-located proteins. Philosophical Transactions of the Royal Society B: Biological Sciences, 375:20190397, May 2020. URL: https://doi.org/10.1098/rstb.2019.0397, doi:10.1098/rstb.2019.0397. This article has 54 citations and is from a domain leading peer-reviewed journal.
(liu2020structuralandfunctional pages 4-5): Qinglian Liu, Ce Liang, and Lei Zhou. Structural and functional analysis of the hsp70/hsp40 chaperone system. Protein Science, 29:378-390, Feb 2020. URL: https://doi.org/10.1002/pro.3725, doi:10.1002/pro.3725. This article has 159 citations and is from a peer-reviewed journal.
(zhang2023jdomainproteinchaperone pages 6-8): Ruobing Zhang, Duccio Malinverni, Douglas M. Cyr, Paolo De Los Rios, and Nadinath B. Nillegoda. J-domain protein chaperone circuits in proteostasis and disease. Jan 2023. URL: https://doi.org/10.1016/j.tcb.2022.05.004, doi:10.1016/j.tcb.2022.05.004. This article has 64 citations and is from a domain leading peer-reviewed journal.
(marszalek2024jdomainproteinsfrom pages 3-4): Jaroslaw Marszalek, Paolo De Los Rios, Douglas Cyr, Matthias P. Mayer, Vasista Adupa, Claes Andréasson, Gregory L. Blatch, Janice E.A. Braun, Jeffrey L. Brodsky, Bernd Bukau, J. Paul Chapple, Charlotte Conz, Sébastien Dementin, Pierre Genevaux, Olivier Genest, Pierre Goloubinoff, Jason Gestwicki, Colin M. Hammond, Justin K. Hines, Koji Ishikawa, Lukasz A. Joachimiak, Janine Kirstein, Krzysztof Liberek, Dejana Mokranjac, Nadinath Nillegoda, Carlos H.I. Ramos, Mathieu Rebeaud, David Ron, Sabine Rospert, Chandan Sahi, Reut Shalgi, Bartlomiej Tomiczek, Ryo Ushioda, Elizaveta Ustyantseva, Yihong Ye, Maciej Zylicz, and Harm H. Kampinga. J-domain proteins: from molecular mechanisms to diseases. Feb 2024. URL: https://doi.org/10.1016/j.cstres.2023.12.002, doi:10.1016/j.cstres.2023.12.002. This article has 25 citations and is from a peer-reviewed journal.
(liu2020structuralandfunctional pages 2-4): Qinglian Liu, Ce Liang, and Lei Zhou. Structural and functional analysis of the hsp70/hsp40 chaperone system. Protein Science, 29:378-390, Feb 2020. URL: https://doi.org/10.1002/pro.3725, doi:10.1002/pro.3725. This article has 159 citations and is from a peer-reviewed journal.
id: A0A8B8L1Z3
gene_symbol: A0A8B8L1Z3
product_type: PROTEIN
status: DRAFT
taxon:
id: NCBITaxon:3816
label: Abrus precatorius
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.
references:
- id: PMID:31775284
title: "Detection of Abrin-Like and Prepropulchellin-Like Toxin Genes and Transcripts Using Whole Genome Sequencing and Full-Length Transcript Sequencing of Abrus precatorius"
existing_annotations: []
core_functions:
- molecular_function:
id: GO:0044183
label: protein folding chaperone
description: >-
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).
locations:
- id: GO:0005737
label: cytoplasm
directly_involved_in:
- id: GO:0006457
label: protein folding
supported_by:
- reference_id: file:ABRPR/A0A8B8L1Z3/A0A8B8L1Z3-deep-research-falcon.md
supporting_text: >-
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
suggested_questions:
- question: >-
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?
- question: >-
Does the IPR053052 (Imprinting Balance Regulator) classification indicate a
role in epigenetic regulation or chromatin remodeling rather than general
protein folding?
- question: >-
Is this protein expressed in specific tissues or developmental stages of
A. precatorius, particularly under stress conditions?
suggested_experiments:
- hypothesis: >-
A0A8B8L1Z3 functions as an Hsp70 cochaperone that stimulates Hsp70 ATPase
activity via its J-domain.
description: >-
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.
experiment_type: biochemical assay
- hypothesis: >-
A0A8B8L1Z3 localizes to the cytoplasm or nucleus, not the ER.
description: >-
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.
experiment_type: fluorescence microscopy