RING-CH finger, H2 subclass (C4HC3-type), found in membrane-associated RING finger protein MARCH1, MARCH8, and similar proteins
This family includes the closely related MARCH1 and MARCH8, both of which are located on endosomes and the plasma membrane and are implicated in regulating cell surface expression of their substrates. They ubiquitylate and downregulate many targets, including major histocompatibility complex class II (MHCII), CD86, transferrin receptor, HLA-DM, and Fas from the cell surface. MARCH1 is mainly expressed in cells of the immune system, while MARCH8 is more broadly expressed. Both of them contain an N-terminal C4HC3-type RING-CH finger, also known as vRING or RINGv, a variant of C3H2C3-type RING-H2 finger, and two transmembrane domains. The cytoplasmic RING-CH domain participates in the ubiquitin transfer from the E2 to its substrate. The transmembrane domains are implicated in target recognition and dimer formation.