Structural analysis of histamine N-methyltransferase gene.

A clone encoding a part of rat histamine N-tele-methyltransferase gene of 11 kb was isolated. The clone contained 4 exons, encoding from 191 to the 3' end of cDNA. The last exon was 692 bases long and specified more than half of the HMT cDNA. A comparison of the sequences of rat and human cDNAs shows that more than one-third of the human 3' untranslated region does not correspond to the rat counterpart, but a homology was found between this region of human cDNA and the 3' franking region of the rat gene. It was found that an exon was interrupted at 4 residues after a glycine residue, which putatively corresponds to the conserved residue among methyltransferases.