Human Histamine N‑Methyltransferase/HNMT Antibody

HNMT (Histamine N-MethylTransferase/HMT) is a 32-34 kDa monomeric member of the HNMT family, methyltransferase superfamily of enzymes. It is found in the cytosol of a variety of cell types including visceral smooth muscle cells, bronchial epithelium, erythrocytes and neurons of the central and peripheral nervous system. HNMT is one of two histamine-processing enzymes in mammals. Following transport of histamine into the cell, HNMT catalyzes the addition of adenosyl-L-Met to histamine, generating N-methylhistamine. Human HNMT is 292 amino acids (aa) in length. It contains one methyl transferase domain (aa 32-216) and three potential Ser phosphorylation sites. The HNMT gene is polymorphic, with single aa changes known to impact activity. There are also two splice variants. One shows a five aa substitution for aa 47-292, while another contains a 63 aa substitution for aa 64-292. The latter isoform is reported to possess a GPI-linkage but show no activity on histamine. Over aa 2-292, human HNMT shares 83% aa sequence identity with mouse HNMT.