This is a RING zinc finger domain found in parkin proteins. Parkin consists of a ubiquitin-like (Ubl) domain and a 60-amino acid linker followed by this domain RING0 and three additional zinc finger domains characteristic of the RBR family. RING0 binds two coordinated zinc atoms at each extremity of the domain with a hairpin. Deletion of RING0 massively derepressed parkin activity supporting the role of RING0 in autoinhibition, point mutations in RING0 (Phe146 to Ala) or RING2 (Phe463 to Ala) both increased parkin activity. The REP (repressor element of parkin) and RING0 domains play a preeminent role in repressing parkin ligase activity through their interactions with RING1 and RING2, respectively [3].

1: Structure of the human Parkin ligase domain in an autoinhibited state. Wauer T, Komander D; EMBO J. 2013;32:2099-2112. PMID:23727886

2: Structure and function of Parkin E3 ubiquitin ligase reveals aspects of RING and HECT ligases. Riley BE, Lougheed JC, Callaway K, Velasquez M, Brecht E, Nguyen L, Shaler T, Walker D, Yang Y, Regnstrom K, Diep L, Zhang Z, Chiou S, Bova M, Artis DR, Yao N, Baker J, Yednock T, Johnston JA; Nat Commun. 2013;4:1982. PMID:23770887

3: Structure of parkin reveals mechanisms for ubiquitin ligase activation. Trempe JF, Sauve V, Grenier K, Seirafi M, Tang MY, Menade M, Al-Abdul-Wahid S, Krett J, Wong K, Kozlov G, Nagar B, Fon EA, Gehring K; Science. 2013;340:1451-1455. PMID:23661642