E3 ubiquitin-protein ligase involved in the establishment of constitutive heterochromatin at pericentric regions by catalyzing histone H3 'Lys-14' monoubiquitination (H3K14ub) (PubMed:41094145). H3K14ub represents a specific tag for heterochromatin formation by facilitating the deposition of histone H3 trimethylated at 'Lys-9' (H3K9me3) (PubMed:41094145). Highly expressed in G2/M phase and associates with mitotic chromosomes in an RNA-dependent manner to catalyze H3K14ub, thereby promoting recruitment of SUV39H (SUV39H1 and/or SUV39H2) and subsequent recruitment of HP1 (CBX1, CBX3 and/or CBX5) proteins to methylated histones (PubMed:41094145). . This is the function of G2E3 (G2/M-phase specific E3 ubiquitin protein ligase, Ensembl gene identifier ENSG00000092140).