Membrane Associated Ring Finger Protein 9 (MARCH9)

MARCH9 is a member of the MARCH family of membrane-bound E3 ubiquitin ligases (EC 6.3.2.19). MARCH enzymes add ubiquitin to target lysines in substrate proteins, thereby signaling their vesicular transport between membrane compartments. MARCH9 induces internalization of several membrane glycoproteins and directs them to the endosomal compartment.the short MARCH9 variant, which they called MARCH9 RINGless, uses a transcription initiation site within intron 2 of the MARCH9 gene. The deduced protein contains the same 2 C-terminal transmembrane domains as full-length MARCH9, but it has a unique 57-amino acid N terminus that replaces the RING-CH domain. Epitope-tagged full-length MARCH9 colocalized with a lysosomal marker. When overexpressed, it also colocalized with the trans-Golgi network (TGN).