RING-CH finger, H2 subclass (C4HC3-type), found in membrane-associated RING-CH11 (MARCH11)
MARCH11, also known as membrane-associated RING finger protein 11, or membrane-associated RING-CH protein XI (MARCH-XI), is a transmembrane RING-finger ubiquitin ligase that is predominantly expressed in developing spermatids in a stage-specific manner and is localized to trans-Golgi network (TGN) vesicles and multivesicular bodies (MVBs). It mediates selective protein sorting via the TGN-MVB transport pathway through its ubiquitin ligase activity. SAMT family proteins have been identified as substrates of MARCH11 in mouse spermatids, suggesting that MARCH11 plays a role in mammalian spermiogenesis. Moreover, MARCH11 targets CD4 for ubiquitination. It also forms complexes with the adaptor protein complex-1 and with fucose-containing glycoproteins including ubiquitinated forms. MARCH11 contains 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. In addition, it harbors a proline-rich region, a tyrosine-based motif, and a PDZ binding motif.
Comment:based on the structure of human MARCH8 with bound Zn2+ ions through its RING-CH finger
Comment:RING-CH finger (C4HC3-type)
Comment:A RING finger typically binds two zinc atoms, with its Cys and/or His side chains in a unique "cross-brace" arrangement.
Comment: The RING fingers found in MARCH proteins have an unusual arrangement of zinc-coordinating residues: The conserved helix complete with tryptophan at the C-terminal end is present but the cysteines and histidines are arranged in the sequence as C4HC3-type, rather than the typical C3H2C3-type in RING-H2 finger.
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