PCGF6 contains a RING finger motif, which is most closely related to those of polycomb group (PcG) proteins RNF110/MEL-18 and BMI1. PcG proteins are known to form protein complexes and function as transcription repressors. This protein has been shown to interact with some PcG proteins and act as a transcription repressor. The activity of this protein is found to be regulated by cell cycle dependent phosphorylation. Alternatively spliced transcript variants encoding different isoforms have been identified.Mouse and human MBLR share 87% sequence identity, and the central domain of MBLR shares 38% identity with the corresponding regions of MEL18 and BMI1. A minor transcript of 4.5 kb was also expressed in some tissues. RT-PCR confirmed ubiquitous expression.