Component of the Clr4 methyltransferase complex (ClrC) which contributes to the establishment of heterochromatin by specifically methylating histone H3 to form H3K9me (PubMed:16024659, PubMed:16040243, PubMed:16157682). ClrC preferentially ubiquitylates H3K14 and ClrC-mediated H3 ubiquitination promotes clr4 methyltransferase activity for the methylation of H3K9 (PubMed:31468675). H3K9me represents a specific tag for epigenetic transcriptional repression by recruiting swi6/HP1 to methylated histones which leads to transcriptional silencing within centromeric heterochromatin, telomeric regions and at the silent mating-type loci (PubMed:16024659, PubMed:16040243, PubMed:16157682, PubMed:18345014). Has a role in both mitotic and meiotic chromosome segregation (PubMed:16040243). Component of the Clr4 methyltransferase complex (ClrC) composed of at least clr4, rik1, pcu4, rbx1, raf1 and raf2. The cullin pcu4, rik1, raf1, raf2 and the ring-box protein rbx1 are components of an E3 ubiquitin ligase, whose activity is essential for heterochromatin assembly (PubMed:16024659). Interacts with pcu4 (PubMed:16157682).