RING-CH finger, H2 subclass (C4HC3-type), found in membrane-associated RING-CH5 (MARCH5)
MARCH5, also known as membrane-associated RING finger protein 5, membrane-associated RING-CH protein V (MARCH-V), RING finger protein 153 (RNF153), or mitochondrial ubiquitin ligase (MITOL), is a mitochondrial outer membrane-associated E3 ubiquitin-protein ligase that regulates mitochondrial dynamics including mitochondrial morphology, transport, and interaction with endoplasmic reticulum (ER), at least in part, through the ubiquitination of mitochondrial fission factor Drp1, microtubule-associated protein 1B (MAP1B) and mitofusin 2 (Mfn2), respectively. MARCH5 also mediates the cell cycle-dependent degradation of Mitofusin 1 (Mfn1) in G2/M phase, and thus serves as an upstream quality controller of Mitofusin 1 (Mfn1), preventing excessive accumulation of Mfn1 protein under stress conditions, which is crucial for mitochondrial homeostasis and cell viability. Moreover, MARCH5 is involved in maintaining mouse-embryonic stem cell (mESC) pluripotency via suppression of ERK signalling. It is also a positive regulator of Toll-like receptor 7 (TLR7)-mediated NF-kappaB activation in mammals. MARCH5 contains an N-terminal C4HC3-type RING-CH finger, also known as vRING or RINGv, a variant of C3H2C3-type RING-H2 finger, and four C-terminal transmembrane spans.
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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