RHOJ (G3V4H1): evidence and exact-input prediction review

The full-length RHOJ/TCL protein is an active, rapidly exchanging GTPase, contrary to a generic GTPase-deficient Rho-family description. However, G3V4H1 is a substantially altered short product, so its activity cannot be decided from the full-length result in either direction.

Input identity and functional boundary

G3V4H1 and Q9H4E5 share HGNC:688. The first 103 residues match exactly; the remainder is highly divergent. The reference guanine-binding residue 136 is not aligned to the target, reference binding residue 177 is not conserved, and the terminal lipidation region is absent from the conserved segment. Retaining the P-loop and switch-region segment alone does not establish a functional G-domain.

Biological evidence

In vitro, TCL shows rapid GDP/GTP
exchange and displays higher GTP dissociation and hydolysis rates than TC10.

Chimeras of TCL and TC10
revealed amino acids 121-129 of TCL contributed to the differences in nucleotide
loading.

Exact non-GO claims

The complete emitted record is preserved in RHOJ-protnlm-source.json. Assessments below address the selected protein product; evidence on longer products is identified explicitly.

Protein name

Cell division control protein 42 homolog

LSP (CS 2) if “homolog” is read as a broad relationship: RHOJ is demonstrably Cdc42-related. The name is less informative than RHOJ/TCL and must not be read as identifying the CDC42 paralog or guaranteeing an intact Cdc42-like enzyme. PMID:10967094(https://pubmed.ncbi.nlm.nih.gov/10967094/).

Function

Binds GTP but lacks intrinsic GTPase activity and is resistant to Rho-specific GTPase-activating proteins

UNC (CS 1) for the selected G3V4H1 product. The “lacks intrinsic GTPase activity” description is contradicted for full-length RHOJ by direct hydrolysis measurements, but the target has a divergent, incomplete G-domain. The conjunction “binds GTP but lacks hydrolysis and resists GAPs” requires binding, hydrolysis and GAP assays of this exact product; a truncation alone does not establish an atypical GTPase mechanism. PMID:10967094(https://pubmed.ncbi.nlm.nih.gov/10967094/); sequence mapping.

Location

Membrane

UNC (CS 1). The selected product does not retain the reference C-terminal membrane-targeting region, and RHOJ membrane association is sensitive to sequence-dependent nucleotide loading. Partner-mediated membrane association remains possible, so no exclusively cytosolic alternative is asserted. PMID:27660391(https://pubmed.ncbi.nlm.nih.gov/27660391/).

No GO or EC term was emitted in this record; the name, function and location assessments above constitute its prediction review.

Family integration

PTHR24072 establishes Rho-family ancestry but includes paralogs with different nucleotide cycling properties. The experimentally characterized RHOJ branch is catalytically active. The selected altered product creates an additional product-integrity boundary beyond family membership.

Evidence limits

The original RHOJ paper is abstract-only in the cache; the 2016 mechanistic study has full text. Neither tests G3V4H1. A confident pseudoenzyme designation would conflate a potentially incomplete product with a stable, evolved GTPase-deficient signaling protein.

Exact sequence mapping: RHOJ-bioinformatics/RESULTS.md. Global alignments can place nonhomologous alternative tails opposite gaps or distant residues; only conserved segments and explicitly retained feature intervals support functional transfer.

Research integration

The genuine Falcon report is retained. Its gene-level synthesis is interpreted through the exact product sequence and the primary sources above; the truncation boundary and paralog distinctions are assessed independently.

2026-10-21 — Full re-review, independent of the ProtNLM2 predictions

Scope: G3V4H1 (ProtNLM2 benchmark target, cohort MOD_EVOLUTION20). No ProtNLM2 file or prediction output was opened or used. New analysis: RHOJ-bioinformatics/compare_sequences_rereview.py -> RESULTS-rereview.txt / RESULTS-rereview.md, which fetch sequences and transcript models live from UniProt and Ensembl. The earlier RESULTS.md and its scripts are unchanged.

Identity of the benchmark accession

Evolutionary grounding

Decisions

All three IEAs (GTPase activity, G protein activity, GTP binding) changed from UNDECIDED to MARK_AS_OVER_ANNOTATED. They are true of the gene and of Q9H4E5 PMID:10967094. They are not supported for an NMD-transcript product that lacks the guanine-base motifs and half the fold. I did not use REMOVE, because no assay of this product exists and the claims are correct at gene level. The description was rewritten so that it gives the gene-level biology [PMID:21628409; PMID:30158707] and then the product-identity boundary. core_functions stays empty, since no function is established for this product. No NEW terms were proposed.

Relative to review next

The canonical product of the same gene, Q9H4E5 (RHOJ_HUMAN, reviewed). genes/human/RHOJ is keyed to G3V4H1, and no review of Q9H4E5 exists in the repo, so the next folder would be genes/human/RHOJ__Q9H4E5. No module names RHOJ or Q9H4E5. These modules use PTHR24072 Rho-family descriptors and are context only: modules/rho_gprotein_signaling.yaml, modules/ephrin_receptor_signaling.yaml, modules/chemokine_signaling.yaml, modules/phagocytic_engulfment.yaml.

2026-10-29: function narrative rescored

The function narrative (RHOJ-protnlm-function-review.md) now scores "binds GTP" as NPI
(DOMAIN_ARCHITECTURE_MISMATCH) for G3V4H1. GTP binding is true of the gene, but guanine binding needs
the G4 (TQID) and G5 (CSAL) motifs, and G3V4H1 keeps only the P-loop, switch I and switch II before
diverging after residue 103. "Lacks intrinsic GTPase activity and is resistant to Rho-specific GAPs"
stays UNC. This supersedes the single UNC given under "Exact non-GO claims" above.
The GO row for GTP binding (GO:0005525) stays MARK_AS_OVER_ANNOTATED, not REMOVE. The two calls rest
on different grounds and are consistent: the narrative score judges whether this exact product can do
what the text says, and the missing G4/G5 motifs refute that; the GO action judges an annotation that
is correct for the gene, and no assay of G3V4H1 exists to justify removing it.