Tetraspan vesicle membrane proteins: Synthesis, subcellular localization, and functional properties

Tetraspan vesicle membrane proteins (TVPs) are characterized by four transmembrane regions and cytoplasmically located end domains. They are ubiquitous and abundant components of vesicles in most, if not all, cells of multicellular organisms. TVP-containing vesicles shuttle between various membranous compartments and are localized in biosynthetic and endocytotic pathways. Based on gene organization and amino acid sequence similarities TVPs can be grouped into three distinct families that are referred to as physins, gyrins, and secretory carrier-associated membrane proteins (SCAMPs). In mammals synaptophysin, synaptoporin, pantophysin, and mitsugumin29 constitute the physins, synaptogyrin 1-…