CG18507

CG18507 encodes the Drosophila member of the TMEM268 family (PANTHER PTHR31193, subfamily SF1; Pfam DUF4481), a predicted multi-pass membrane protein. The fly protein has a long, largely disordered and low-complexity N-terminal extension (about residues 1-226) that has no counterpart in vertebrate TMEM268, followed by a conserved core that aligns to human TMEM268 and contains two predicted transmembrane helices (residues 292-310 and 316-339). The gene produces several alternative products that differ only at their C-termini. In the embryo, CG18507 mRNA is expressed in the developing tracheal system, where its expression depends on the bHLH-PAS transcription factor Trachealess. In mammals, TMEM268 localizes to the endoplasmic reticulum and plasma membrane and stabilizes integrin subunits (beta4 integrin in gastric cancer cells, CD11b in phagocytes) by limiting their degradation; flies lack orthologs of those integrin partners, and no molecular activity, partner, membrane compartment or loss-of-function phenotype has been established for CG18507 itself.