This family represents the first three transmembrane regions of 11-TM proteins involved in vesicle transport. In S. cerevisiae these proteins are members of the yeast facilitator superfamily and are integral membrane proteins localised to the cell periphery, in particular to the bud-neck region. The distribution is consistent with a role in late exocytosis which is in agreement with the proteins' ability to substitute for the function of Sro7p, required for the sorting of the protein Enap1 into Golgi-derived vesicles destined for the cell surface [1].

1: The yeast tumor suppressor homologue Sro7p is required for targeting of the sodium pumping ATPase to the cell surface. Wadskog I, Forsmark A, Rossi G, Konopka C, Oyen M, Goksor M, Ronne H, Brennwald P, Adler L; Mol Biol Cell. 2006;17:4988-5003. PMID:17005914