Enables N-methyltransferase activity and RNA polymerase II-specific DNA-binding transcription factor binding activity. Involved in actin modification; peptidyl-histidine methylation; and regulation of uterine smooth muscle contraction. Acts upstream of or within positive regulation of muscle cell differentiation and positive regulation of transcription by RNA polymerase II. Located in chromatin. Orthologous to human SETD3 (SET domain containing 3, actin histidine methyltransferase). [provided by Alliance of Genome Resources, Apr 2022]