MARCH4 is a member of the MARCH family of membrane-bound E3 ubiquitin ligases (EC 6.3.2.19). MARCH enzymes add ubiquitin (see MIM 191339) to target lysines in substrate proteins, thereby signaling their vesicular transport between membrane compartments. MARCH4 reduces surface accumulation of several membrane glycoproteins by directing them to the endosomal compartment (Bartee et al., 2004 [PubMed 14722266]).[supplied by OMIM, Apr 2010].