RING-CH finger, H2 subclass (C4HC3-type), found in membrane-associated RING-CH proteins (MARCH)
This family of membrane-associated E3 ubiquitin ligases consists of 11 members in mammals (MARCH1-11), which are characterized by containing an N-terminal C4HC3-type RING-CH finger, also known as vRING or RINGv, a variant of the C3H2C3-type RING-H2 finger). Most family members have hydrophobic transmembrane regions and are localized to the plasma membrane and intracellular organelle membrane. Only MARCH7 and MARCH10 are predicted to have no transmembrane spanning region. MARCH proteins have been implicated in mediating the ubiquitination and subsequent down-regulation of cell-surface immune regulatory molecules, such as major histocompatibility complex class II and CD86, as well as in endoplasmic reticulum-associated degradation, endosomal protein trafficking, mitochondrial dynamics, and spermatogenesis.
Structure:2D8S; Homo sapiens MARCH8 binds two Zn2+ ions through its RING-HC 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.",