|Detection of Human Histamine N-Methyltransferase/HNMT by Western Blot. Western blot shows lysates of HepG2 human hepatocellular carcinoma cell line, HeLa human cervical epithelial carcinoma cell line, human stomach tissue, human kidney tissue, and human lung tissue. PVDF membrane was probed with 0.5 µg/mL of Sheep Anti-Human Histamine N-Methyltransferase/HNMT Antigen Affinity-purified Polyclonal Antibody (Catalog # AF7637) followed by HRP-conjugated Anti-Sheep IgG Secondary Antibody (Catalog # HAF016). A specific band was detected for Histamine N-Methyltransferase/HNMT at approximately 32 kDa (as indicated). This experiment was conducted under reducing conditions and using Immunoblot Buffer Group 1.|
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.