Polycomb group (PcG) proteins form multiprotein complexes that regulate expression patterns of developmental and cell proliferation genes. Several members of the PcG contain ring finger domains and are identified as a subclass of RING finger proteins. The RING-type zinc finger motif is present in a number of viral and eukaryotic proteins and is made of a conserved cysteine-rich domain that is able to bind two zinc atoms. Proteins that contain the RING-type zinc finger conserved domain are generally involved in the ubiquitination pathway of protein degradation. PCGF6 (polycomb group ring finger 6), also known as MBLR or RNF134, is a 350 amino acid nuclear protein that is ubiquitously expressed and contains one RING-type zinc finger. PCGF6 acts as a transcriptional repressor and regulates the level of histone H3K4Me3 by activating SmcY histone demethylase. PCGF6 exists as two alternatively spliced isoforms.
Mel18 and Bmi1-like RING finger; Mel18 and Bmi1-like RING finger protein; Mel18- and Bmi1-like RING finger protein; Polycomb group RING finger protein 6; RING finger protein 134