RING finger, HC subclass, found in midline-1 (MID1), midline-2 (MID2) and similar proteins
MID1, also known as midin, midline 1 RING finger protein, putative transcription factor XPRF, RING finger protein 59 (RNF59), or tripartite motif-containing protein 18 (TRIM18), is a microtubule-associated E3 ubiquitin-protein ligase implicated in epithelial-mesenchymal differentiation, cell migration and adhesion, and programmed cell death along specific regions of the ventral midline during embryogenesis. MID2, also known as midin-2, midline defect 2, RING finger protein 60 (RNF60), or tripartite motif-containing protein 1 (TRIM1), associates with the microtubule network and may at least partially compensate for the loss of MID1. Both MID1 and MID2 interacts with Alpha 4, which is a regulatory subunit of PP2-type phosphatases, such as PP2A, and an integral component of the rapamycin-sensitive signaling pathway. They also play a central role in the regulation of granule exocytosis. Functional redundancy exists between MID1 and MID2 in cytotoxic lymphocytes (CTL). Both MID1 and MID2 belong to the C-I subclass of the TRIM (tripartite motif) family of proteins that are defined by their N-terminal RBCC (RING, Bbox, and coiled coil) domains, including three consecutive zinc-binding domains, a C3HC4-type RING-HC finger, Bbox1 and Bbox2, and a coiled coil region, as well as a COS (carboxyl-terminal subgroup one signature) box, a fibronectin type III (FN3) domain, and a B30.2/SPRY (SplA and ryanodine receptor) domain positioned C-terminal to the RBCC domain.
Comment:C3HC4-type RING-HC finger consensus motif: C-X2-C-X(9-39)-C-X(1-3)-H-X(2-3)-C-X2-C-X(4-48)-C-X2-C, where X is any amino acid and the number of X residues varies in different fingers
Comment:A RING finger typically binds two zinc atoms, with its Cys and/or His side chains in a unique "cross-brace" arrangement.
Jiyao W et al.(2023). "The conserved domain database in 2023.",