The IBR (In Between Ring fingers) domain is often found to occur between pairs of ring fingers. This domain has also been called the C6HC domain and DRIL (for double RING finger linked) domain [ PUBMED:10422847 ]. Proteins that contain two Ring fingers and an IBR domain (these proteins are also termed RBR family proteins) … expand

The IBR (In Between Ring fingers) domain is often found to occur between pairs of ring fingers. This domain has also been called the C6HC domain and DRIL (for double RING finger linked) domain [ PUBMED:10422847 ]. Proteins that contain two Ring fingers and an IBR domain (these proteins are also termed RBR family proteins) are thought to exist in all eukaryotic organisms. RBR family members play roles in protein quality control and can indirectly regulate transcription [ PUBMED:15152079 ]. Evidence suggests that RBR proteins are often parts of cullin-containing ubiquitin ligase complexes. The ubiquitin ligase Parkin is an RBR family protein whose mutations are involved in forms of familial Parkinson's disease [ PUBMED:15152079 ].

IBR domain is a cysteine-rich (C6HC) zinc finger domain that is present in Triad1, and which is conserved in other proteins encoded by various eukaryotes. The C6HC consensus pattern is:

C-x(4)-C-x(14-30)-C-x(1-4)-C-x(4)-C-x(2)-C-x(4)-H-x(4)-C

The C6HC zinc finger motif is the fourth family member of the zinc-binding RING, LIM, and LAP/PHD fingers. Strikingly, in most of the proteins the C6HC domain is flanked by two RING finger structures IPR001841. The novel C6HC motif has been called DRIL (double RING finger linked). The strong conservation of the larger tripartite TRIAD (twoRING fingers and DRIL) structure indicates that the three subdomains are functionally linked and identifies a novel class of proteins [ PUBMED:10422847 ].