The function of Ensembl gene identifier ENSG00000181090 (EHMT1, euchromatic histone lysine methyltransferase 1) is as follows. Histone methyltransferase that specifically mono-, di- and trimethylates 'Lys-9' of histone H3 (H3K9me1, H3K9me2 and H3K9me3, respectively) in euchromatin (PubMed:12004135). H3K9me represents a specific tag for epigenetic transcriptional repression by recruiting HP1 proteins to methylated histones (PubMed:12004135). Also weakly methylates 'Lys-27' of histone H3 (H3K27me) (PubMed:12004135). Also required for DNA methylation, the histone methyltransferase activity is not required for DNA methylation, suggesting that these 2 activities function independently (By similarity). Probably targeted to histone H3 by different DNA-binding proteins like E2F6, MGA, MAX and/or DP1 (PubMed:12004135). During G0 phase, it probably contributes to silencing of MYC- and E2F-responsive genes, suggesting a role in G0/G1 transition in cell cycle (PubMed:12004135). Involved in the differentiation of myoblastic precursors into brown adipose cells: following recruitment to chromatin by PRDM16, mediates formation of H3K9me2 and H3K9me3, inhibiting the expression of white adipose- selective genes (By similarity). Also involved in the differentiation of beige adipocytes from white adipose cells following recruitment by PRDM16 (By similarity). EHMT1 also promotes protein stabilization of PRDM16, by preventing PRDM16 ubiquitination and degradation (By similarity). In addition to the histone methyltransferase activity, also methylates non-histone proteins: mediates dimethylation of 'Lys- 373' of p53/TP53 (PubMed:20118233). Represses the expression of mitochondrial function-related genes, perhaps by occupying their promoter regions, working in concert with probable chromatin reader BAZ2B (By similarity). {ECO:0000250|UniProtKB:Q5DW34, ECO:0000269|PubMed:12004135, ECO:0000269|PubMed:20118233}.