Enables N-methyltransferase activity. Predicted to be involved in histamine catabolic process and methylation. Predicted to act upstream of or within regulation of neurotransmitter levels. Predicted to be located in several cellular components, including centrosome; neuron projection; and nucleoplasm. Predicted to be active in cytosol. Human ortholog(s) of this gene implicated in Parkinson's disease; asthma; atopic dermatitis; autosomal recessive non-syndromic intellectual disability; and essential tremor. Orthologous to human HNMT (histamine N-methyltransferase). [provided by Alliance of Genome Resources, Apr 2022]