RING-CH finger, H2 subclass (C4HC3-type), found in membrane-associated RING-CH9 (MARCH9)
MARCH9, also known as membrane-associated RING finger protein 9, membrane-associated RING-CH protein IX (MARCH-IX), or RING finger protein 179 (RNF179), is a transmembrane E3 ubiquitin-protein ligase that down-regulates Mult1, CD4, major histocompatibility complex-I (MHC), and intercellular adhesion molecule (ICAM-1). It may also interact with receptor-type protein-tyrosine phosphatases (e.g. PTPRJ/CD148) as well as Fc gamma receptor IIB (CD32B), HLA-DQ, signaling lymphocytic activation molecule (CD150), and polio virus receptor (CD155). MARCH9 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.
Jiyao W et al.(2023). "The conserved domain database in 2023.",