This family contains several eukaryotic transmembrane proteins which are homologous to human transmembrane protein 9 Swiss:Q9P0T7. The TMEM9 gene encodes a 183 amino-acid protein that contains an N-terminal signal peptide, a single transmembrane region, three potential N-glycosylation sites and three conserved cys-rich domains in the N-terminus, but no known functional domains. The protein is highly conserved between species from Caenorhabditis elegans to man and belongs to a novel family of transmembrane proteins. The exact function of TMEM9 is unknown although it has been found to be widely expressed and localised to the late endosomes and lysosomes [1]. Members of this family contain Pfam:PF03128 repeats in their N-terminal region.

1: Characterization of the novel human transmembrane protein 9 (TMEM9) that localizes to lysosomes and late endosomes. Kveine M, Tenstad E, Dosen G, Funderud S, Rian E; Biochem Biophys Res Commun 2002;297:912-917. PMID:12359240