CG32354 (FlyBase FBgn0052354; current UniProt gene name CG7159) encodes an uncharacterized 662-residue Drosophila protein built from seven follistatin/Kazal-like cysteine-rich domains preceded by a single hydrophobic segment (residues 57-78) and no N-terminal signal peptide, suggesting a membrane-anchored protein with an extracellular Kazal-domain array, though its topology has not been tested. It belongs to the arthropod-specific PANTHER subfamily PTHR10913:SF79 of the follistatin-related family; its nearest characterised relatives are the fly follistatin Fs (a paralog from an arthropod-level duplication) and, more distantly, the human co-orthologs SPINK5 and TMEFF1/2. No target-specific biochemical, genetic or localization study exists; the only literature report places it among Spitz-responsive genes expressed in the peripodial epithelium of the eye imaginal disc. Whether its Kazal domains inhibit serine proteases, bind growth factors, or play another extracellular role is unknown.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0004867 serine-type endopeptidase inhibitor activity | IEA GO_REF:0000104 | UNDECIDED | Summary: Serine-type endopeptidase inhibitor activity is a plausible but untested hypothesis from the Kazal-domain architecture; phylogenetic evidence does not support transfer. Reason: The IEA comes from a UniRule assignment triggered by Kazal-type domain signatures. The domains are of the follistatin-type Kazal (KAZAL_FS) class, which in follistatin, agrin and TMEFF proteins mostly lacks protease-inhibitory activity. In the PANTHER 19 tree the only PAINT assertion of GO:0004867 in PTHR10913 is placed on PTN000099251 (Theria, seed SPINK5), not on any ancestor of CG32354, so PAINT curators deliberately did not propagate inhibitor activity to the Ecdysozoa clade. The seven predicted reactive-bond sites carry mixed P1 residues (P, T, S, K, K, R, R), and UniProt cautions that the rule lacks conserved residues for feature propagation. Some K/R P1 sites leave inhibition possible, so the claim is neither supported nor refuted; no assay exists. Supporting Evidence: file:DROME/CG32354/CG32354-uniprot.txt DR InterPro; IPR002350; Kazal_dom. file:DROME/CG32354/CG32354-uniprot.txt DR CDD; cd00104; KAZAL_FS; 6. file:DROME/CG32354/CG32354-uniprot.txt DR PROSITE; PS51465; KAZAL_2; 7. file:DROME/CG32354/CG32354-uniprot.txt CC -!- CAUTION: Lacks conserved residue(s) required for the propagation of CC feature annotation. {ECO:0000256|PROSITE-ProRule:PRU00798}. file:DROME/CG32354/CG32354-bioinformatics/RESULTS-rereview.md The serine-type endopeptidase inhibitor IBD (PTN000099251, taxon:32525 Theria, seed SPINK5) and the activin-binding IBDs (PTN001657053, taxon:6072) are not on the Q9VSK1 path file:DROME/CG32354/CG32354-bioinformatics/RESULTS-rereview.md The seven PROSITE PRU00798 reactive-bond sites carry P1 residues P, T, S, K, K, R and R. |
| GO:0005576 extracellular region | IBA GO_REF:0000033 | KEEP AS NON CORE | Summary: Extracellular localization of the Kazal-domain array is inherited from the family root and is consistent with the architecture, but the exact topology (membrane-anchored vs secreted) is unresolved. Reason: PTN000099217 is the Eukaryota root of the PTHR10913 tree and an ancestor of CG32354 in the PANTHER 19 tree, so the IBA follows from a sound root-level placement: all characterised family members act outside the cell. CG32354 has no N-terminal signal peptide but a single predicted helix at 57-78, so it may be a signal-anchored membrane protein whose Kazal domains face the extracellular space rather than a freely secreted protein. Extracellular region is retained as the most precise location the evidence supports; plasma membrane or cell surface cannot be asserted without topology data. It is kept as non-core because it says nothing about the protein's activity. Propagation Review Root cause: NO FAILURE NON CORE Sources checked: PANTHER:PTN000099217 SUPPORTS TRANSFER Family root node (Eukaryota speciation) on the Q9VSK1 root-to-leaf path in the PANTHER 19 PTHR10913 tree; seeded by fly Fs, FSTL3, FST, SPINK5 and others, all extracellular. Supporting Evidence: file:DROME/CG32354/CG32354-bioinformatics/RESULTS-rereview.md Q9VSK1 descends from both PAINT nodes that give it IBA annotations: PTN000099217 (Eukaryota, family root, extracellular region) file:DROME/CG32354/CG32354-uniprot.txt FT TRANSMEM 57..78 FT /note="Helical" FT /evidence="ECO:0000256|SAM:Phobius" file:DROME/CG32354/CG32354-uniprot.txt DR InterPro; IPR002350; Kazal_dom. |
| GO:0030154 cell differentiation | IBA GO_REF:0000033 | KEEP AS NON CORE | Summary: Broad family-level developmental assertion inherited from the Eumetazoa duplication node; untested for CG32354 and non-core. Reason: The earlier review left this UNRESOLVED because the cached PAINT slice gave PTN000099219 no taxon. The PANTHER 19 tree shows PTN000099219 is the Eumetazoa duplication node directly beneath the family root and is an ancestor of CG32354, so CG32354 lies inside the clade to which PAINT assigned cell differentiation. Its seeds include the fly paralogs CG12716 and anon-f, which share the Hexapoda-Crustacea duplication node with CG32354, and follistatin-family proteins from vertebrates. There is no target-specific evidence of loss or divergence, so the IBA is not removed. The term is very broad, CG32354 has no developmental assay, and the eye-disc expression screen shows only Spitz-responsive expression. It is therefore kept as non-core rather than accepted as a defined function. Propagation Review Root cause: NO FAILURE NON CORE Sources checked: PANTHER:PTN000099219 SUPPORTS TRANSFER Eumetazoa duplication node beneath the PTHR10913 root, on the Q9VSK1 path in the PANTHER 19 tree; heterogeneous seeds including fly CG12716 and anon-f. Supports only a broad developmental role, no specific differentiation process. Supporting Evidence: file:DROME/CG32354/CG32354-bioinformatics/RESULTS-rereview.md PTN000099219 (Eumetazoa duplication, cell differentiation) PMID:17553483 10 genes upregulated in GMR>sSpi: CG32354 |
Loading supporting content…
Download this section (compressed HTML)Q: Is the hydrophobic segment at residues 57-78 an uncleaved signal anchor (type II membrane protein) or a cleaved internal signal peptide that releases the Kazal array as a secreted protein?
Q: Do any of the Kazal-like domains with K/R at the predicted P1 position (386, 457, 509, 612) inhibit trypsin-like serine proteases, or does CG32354 instead bind growth factors as its paralog Fs does?
Experiment: Express epitope-tagged CG32354 in S2 cells or imaginal discs and test surface exposure versus secretion (non-permeabilized staining, medium immunoblot) to resolve topology.
Experiment: Test recombinant Kazal-domain fragments against a panel of serine proteases (trypsin, chymotrypsin, elastase, fly immune proteases) to establish or exclude inhibitory activity.
Loading supporting content…
Download this section (compressed HTML)Loading supporting content…
Download this section (compressed HTML)Loading supporting content…
Download this section (compressed HTML)