This family of membrane proteins consists of Type II secretion system protein M sequences from several Gram-negative (diderm) bacteria. The precise function of these proteins is unknown, though in Vibrio cholerae, the T2SM (EpsM) protein interacts with the T2SL (EpsL) protein, and also forms homodimers [1].

1: Direct interaction of the EpsL and EpsM proteins of the general secretion apparatus in Vibrio cholerae. Sandkvist M, Hough LP, Bagdasarian MM, Bagdasarian M; J Bacteriol 1999;181:3129-3135. PMID:10322014

2: The general secretory pathway: a general misnomer?. Desvaux M, Parham NJ, Scott-Tucker A, Henderson IR; Trends Microbiol. 2004;12:306-309. PMID:15223057

3: Type II protein secretion and its relationship to bacterial type IV pili and archaeal flagella. Peabody CR, Chung YJ, Yen MR, Vidal-Ingigliardi D, Pugsley AP, Saier MH Jr; Microbiology. 2003;149:3051-3072. PMID:14600218

4: Secretion and subcellular localizations of bacterial proteins: a semantic awareness issue. Desvaux M, Hebraud M, Talon R, Henderson IR; Trends Microbiol. 2009;17:139-145. PMID:19299134