AT4G38370

UniProt ID: Q0WW53
Organism: Arabidopsis thaliana
Review Status: COMPLETE
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Gene Description

AT4G38370 encodes a 225-residue protein made of a single histidine-phosphatase superfamily branch-1 domain (the phosphoglycerate-mutase-like fold, Pfam PF00300). It belongs to PANTHER family PTHR47821, a lineage found in land plants, green and other algae, choanoflagellates, fungi and some bacteria that has no experimentally characterised member. The protein retains the catalytic apparatus of the fold: the N-terminal RHG motif histidine (His17) that forms the phosphohistidine intermediate, the glutamate proton donor/acceptor (Glu109) and the C-terminal histidine (His173) that stabilises the transition state, so it is probably an active phosphotransfer enzyme (a phosphomonoesterase or mutase). Its substrate, its reaction (hydrolysis versus intramolecular transfer), its subcellular location and its biological role have not been established experimentally. The protein has been detected by proteomics.

Core Functions

Predicted histidine-dependent phosphotransfer catalysis by a histidine phosphatase superfamily branch-1 domain. The fold's catalytic residues are retained (RHG-motif His17 nucleophile, Glu109 proton donor/acceptor, His173 transition-state stabiliser), but the substrate and whether the reaction is a hydrolysis or a mutase-type transfer are unknown, so no GO molecular function more specific than catalytic activity can be justified. No molecular function term is asserted.

Supporting Evidence:
  • file:ARATH/AT4G38370/AT4G38370-bioinformatics/RESULTS-rereview.md
    | Active site: Tele-phosphohistidine intermediate | | H11 | H17 |
  • file:ARATH/AT4G38370/AT4G38370-bioinformatics/RESULTS-rereview.md
    | Active site: Proton donor/acceptor | | E89 | E109 |
  • file:ARATH/AT4G38370/AT4G38370-uniprot.txt
    DR Pfam; PF00300; His_Phos_1; 1.

References

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Suggested Questions for Experts

Q: Which phosphomonoester substrates, if any, are turned over by purified AT4G38370?

Q: Is the PTHR47821 lineage a phosphatase (hydrolase) or a cofactor-dependent mutase, and is its substrate conserved between the plant, algal, fungal and bacterial members?

Q: The TAIR GO rows for this locus (ND molecular function, ND biological process, nucleus by ISM) sit on the reference-proteome entry F4JTN4, which is identical in sequence to Q0WW53; should annotation for At4g38370 be consolidated on F4JTN4?

Suggested Experiments

Experiment: Express recombinant AT4G38370 and an H17A mutant; screen a phosphometabolite panel (2,3-bisphosphoglycerate and 2-/3-phosphoglycerate with and without 2,3-BPG cofactor, sugar phosphates and bisphosphates, phosphoserine, glycerol phosphates, nucleotides, p-nitrophenyl phosphate) across a pH range, measuring phosphate release and products by LC-MS, and compare kinetics of wild type and mutant.

Hypothesis: AT4G38370 is an active histidine-dependent phosphatase or mutase whose activity depends on His17.

Type: in vitro enzyme activity screen with catalytic mutant

Experiment: Untargeted and targeted phosphometabolite profiling of independent AT4G38370 null alleles versus wild type, with complementation by the wild type and the H17A allele; determine subcellular location with a native promoter fluorescent fusion.

Hypothesis: The physiological substrate of AT4G38370 accumulates in loss-of-function plants.

Type: metabolomics of loss-of-function mutants with localization

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 · AT4G38370-protnlm-predictions-review.yaml · Review status: COMPLETE

AT4G38370 (Q0WW53, sequence-identical to F4JTN4) is a single-domain histidine-phosphatase superfamily branch-1 protein in PANTHER family PTHR47821, which has no experimentally characterized member. It retains the RHG-motif nucleophile histidine, the proton donor/acceptor glutamate and the C-terminal transition-state histidine of the fold, so catalytic activity is plausible, but no assay of the protein or of any family member establishes it, and the gene carries only an ND molecular-function annotation.

Source documents: genes/ARATH/AT4G38370/AT4G38370-protnlm-source.json · genes/ARATH/AT4G38370/AT4G38370-notes.md

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

GO:0003824 catalytic activity GO_MF
UNC — Uncertain Review score: 1/2
Prediction method: ProtNLM2 · Version: UniProt API snapshot 2026-09-10 · file:ARATH/AT4G38370/AT4G38370-protnlm-source.json
Review rationale: Catalytic activity is a novel term for this gene, whose only molecular-function annotation (on the identical entry F4JTN4) is ND. Local alignment maps the curated phosphohistidine nucleophile, proton donor/acceptor and transition-state stabilizer of human PGAM1 and E. coli GpmA onto His17, Glu109 and His173 of Q0WW53, so the catalytic apparatus of the histidine-phosphatase fold is retained and enzymatic activity is plausible. However, these comparators lie outside PANTHER PTHR47821, no member of that family has been assayed, and PubMed searches for At4g38370, Q0WW53 and F4JTN4 return no functional study. Residue retention does not prove activity, and both gene reviews decline to assert any molecular-function term, so the prediction can be neither validated nor refuted.
Supporting Evidence:

Deep Research

Falcon

(AT4G38370-deep-research-falcon.md)

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📚 Additional Documentation

Notes

(AT4G38370-notes.md)

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Bioinformatics Results

(RESULTS.md)

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📄 View Raw YAML

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