A0A2G9RZF1

Review rationale: The target is a 156-residue fragment of bullfrog TLL1: residues 30-156 match the last 127 residues (CUB5) of the complete bullfrog TLL1 model at 126/127 identity, and identity to other tolloids follows the TLL1 orthogroup. The fragment carries only a CUB domain, with no S1 serine-protease domain and no His-Asp-Ser triad. That excludes the ovochymase-like egg-envelope protease mechanism the prediction implies, for both the fragment and the gene. The complete TLL1 product is an astacin-type metalloprotease that processes procollagen C-propeptides and cleaves chordin, and the PTHR24251 family review finds that single fertilization is not a family-wide process. These facts exclude the predicted mechanism, not every way TLL1 could take part in fertilization. TLL1 has no known mechanism of participation in fertilization, so no missing feature can be shown to be required, and a non-catalytic CUB-mediated binding or extracellular-matrix role at the egg surface is neither shown nor excluded. PubMed searches for tolloid-like proteins in fertilization and for bullfrog tolloids returned no reports either way. The evidence is an absence of support, not a positive refutation, so the prediction is uncertain.

DOMAIN ARCHITECTURE MISMATCH

Review rationale: The sequence ProtNLM2 was given is a 156-residue fragment of bullfrog TLL1. Residues 30-156 are the C-terminal CUB5 domain, at 126/127 identity to the last 127 residues of the complete 1005-aa bullfrog TLL1 model, and residues 1-29 align to no tolloid model. The fragment lacks the TLL1 N-terminal signal peptide, the feature that routes the complete product into the secretory pathway and so to the extracellular region. Its UniProt record has no signal-peptide or transmembrane feature, only the CUB domain at 31-147. Extracellular region is true of the complete TLL1 product (human TLL1 activity is measured in the extracellular medium of transfected cells, and PANTHER places the term at the tolloid node), but the product encoded by this accession has no secretion signal, so the location is not supported for this sequence. GOA has no annotation for this accession.