Protein-histidine N-methyltransferase that specifically catalyzes 1-methylhistidine (pros-methylhistidine) methylation of target proteins (, ). Mediates methylation of proteins with a His-x-His (HxH) motif (where 'x' is preferably a small amino acid) . Catalyzes methylation of target proteins such as S100A9, NDUFB3, SLC39A5, SLC39A7, ARMC6 and DNAJB12; 1-methylhistidine modification may affect the binding of zinc and other metals to its target proteins (, ). Constitutes the main methyltransferase for the 1-methylhistidine modification in cell .
Subcellular locations: Endoplasmic reticulum, Mitochondrion
Colocalizes with membranous compartments such as the endoplasmic reticulum and mitochondria.