RING finger, HC subclass, found in SH3 domain-containing RING finger protein 1 (SH3RF1) and similar proteins
SH3RF1, also known as plenty of SH3s (POSH), RING finger protein 142 (RNF142), or SH3 multiple domains protein 2 (SH3MD2), is a trans-Golgi network-associated pro-apoptotic scaffold protein with E3 ubiquitin-protein ligase activity. It also plays a role in calcium homeostasis through the control of the ubiquitin domain protein Herp. It may also have a role in regulating death receptor mediated and c-Jun N-terminal kinase (JNK) mediated apoptosis, linking Rac1 to downstream components. SH3RF1 also enhances the ubiquitination of ROMK1 potassium channel resulting in its increased endocytosis. Moreover, SH3RF1 assembles an inhibitory complex with the actomyosin regulatory protein Shroom3, which links to the actin-myosin network to regulate neuronal process outgrowth. It also forms a complex with apoptosis-linked gene-2 (ALG-2) and ALG-2-interacting protein (ALIX/AIP1) in a calcium-dependent manner to play a role in the regulation of the JNK pathway. Furthermore, direct interaction of SH3RF1 and another molecular scaffold JNK-interacting protein (JIP) is required for apoptotic activation of JNKs. Interaction of SH3RF1 and E3 ubiquitin-protein isopeptide ligases, Siah proteins, further promotes JNK activation and apoptosis. In addition, SH3RF1 binds to and degrades TAK1, a crucial activator of both the JNK and the Relish signaling pathways. SH3RF1 contains an N-terminal C3HC4-type RING-HC finger responsible for the E3 ligase activity and four Src Homology 3 (SH3) domains, which are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs.
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.",