RING finger, HC subclass, found in RING finger proteins RNF212, RNF212B and similar proteins
The family includes RING finger protein RNF212, RNF212B, and their homologs. RNF212 is a dosage-sensitive regulator of crossing-over during mammalian meiosis. It plays a central role in designating crossover sites and coupling chromosome synapsis to the formation of crossover-specific recombination complexes. It also functions as an E3 ligase for small ubiquitin-related modifier (SUMO) modification. RNF212B shows high sequence similarity with RNF212, but its biological function remains unclear. Members in this family contain an N-terminal C3HC4-type RING-HC finger. The family also includes two homologs of RNF212, meiotic procrossover factors Zip3 and ZHP-3, which have been identified in Saccharomyces cerevisiae and Caenorhabditis elegans, respectively. Budding yeast Zip3 is a small ubiquitin-related modifier (SUMO) E3 ligase implicated in the SUMO pathway of post-translational modification. It sumoylates chromosome axis proteins, thus promoting synaptonemal complex polymerization. It also acts as a Smt3 E3 ligase. Zip3 includes a SUMO Interacting Motif (SIM) and a modified C3HCHC2-type RING-HC finger that are important for Zip3 in vitro E3 ligase activity and necessary for SC polymerization and correct sporulation. ZHP-3 acts at crossovers to couple meiotic recombination with synaptonemal complex disassembly and chiasma formation in Caenorhabditis elegans. It possess a C3HC4-type RING-HC finger.