SMIM36 (small integral membrane protein 36) is a 93-amino-acid (about 10 kDa) protein encoded on chromosome 17q22. It has a single predicted helical transmembrane segment near the N-terminus (residues 14-34), followed by a cytoplasmic or luminal segment of about 60 residues whose last 20 residues are predicted to be disordered and are rich in proline and glycine. It defines its own small protein family (Pfam SMIM36), with no recognised relationship to characterised proteins. Orthologues are found across bony vertebrates, including teleost fish. The protein has been detected by mass spectrometry, and its RNA is enriched in retina and testis. Its membrane localisation is predicted from sequence; the specific membrane, topology, partners and biological role are unknown. An intronic SMIM36 variant was associated with response to IL-17 pathway inhibitors in a small psoriasis cohort, but that variant is an expression QTL for the neighbouring MMD gene and says nothing about the SMIM36 protein. No functional study of SMIM36 has been published.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0016020 membrane | IEA GO_REF:0000044 | ACCEPT | Summary: UniProt subcellular-location mapping to membrane, based on the single predicted helical transmembrane segment (residues 14-34). Reason: Correct, though general. A 21-residue hydrophobic helix in a 93-residue protein makes SMIM36 a single-pass integral membrane protein. No experiment identifies the specific membrane, so a more precise location cannot be given. This is the only annotation the gene carries and the only one the evidence supports. Supporting Evidence: file:human/SMIM36/SMIM36-uniprot.txt FT TRANSMEM 14..34 file:human/SMIM36/SMIM36-uniprot.txt CC -!- SUBCELLULAR LOCATION: Membrane {ECO:0000255}; Single-pass membrane |
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Download this section (compressed HTML)Q: In which membrane and with which topology does SMIM36 reside in photoreceptors or spermatogenic cells, the cell types where its RNA is most abundant?
Q: Is the proline/glycine-rich disordered C-terminal tail a binding site for SH3, WW or other proline-recognising domains?
Experiment: Tag the endogenous locus in rat or zebrafish (Ensembl Compara lists orthologues in both but none in mouse), localise the protein in retina and testis with organelle markers, and identify partners of the C-terminal tail by proximity labelling. A zebrafish mutant would show whether the gene is needed for vision or fertility.
Hypothesis: SMIM36 is a single-pass membrane protein of a defined compartment in retina or testis.
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