RING-CH finger, H2 subclass (C4HC3-type), found in membrane-associated RING-CH4 (MARCH4)
MARCH4, also known as membrane-associated RING finger protein 4, membrane-associated RING-CH protein IV (MARCH-IV), or RING finger protein 174 (RNF174), is a transmembrane E3 ubiquitin-protein ligase that down-regulates the tetraspanin CD81 and major histocompatibility complex-I (MHC). It also associates with Mult1, suppressing Mult1 expression at the cell surface in a lysine-dependent manner that can be reversed by heat shocking the cells. MARCH4 contains an N-terminal C4HC3-type RING-CH finger, also known as vRING or RINGv, a variant of C3H2C3-type RING-H2 finger, followed by two transmembrane regions.
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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