Phenylethanolamine-N-Methyltransferase (PNMT)

Phenylethanolamine N-methyltransferase (PNMT; EC 2.1.1.28) catalyzes the synthesis of epinephrine from norepinephrine, the last step of catecholamine biosynthesis. The nucleotide sequence showed that human PNMT has 282 amino acid residues with a predicted molecular weight of 30,853, including the initial methionine. The amino acid sequence was 88% homologous to that of bovine enzyme.A hybrid gene consisting of 2 kb of the PNMT 5-prime-flanking region fused to the simian virus 40 early region also resulted in tumor antigen mRNA expression in adrenal glands and eyes; furthermore, immunocytochemistry showed that the tumor antigen was localized in nuclei of adrenal medullary cells and cells of the inner nuclear cell layer of the retina, both prominent sites of epinephrine synthesis.