title: Localization of membrane-bound catechol-O-methyltransferase.
abstract: Previous studies of the distribution of catechol-O-methyltransferase (COMT) have concentrated on the soluble enzyme activity. In this study the activity of the membrane-bound enzyme was determined in different brain regions and peripheral tissues of the rat. Membrane-bound COMT, like the soluble enzyme, has a general distribution with high levels in liver, kidney, and vas deferens. However, the ratio of membrane-bound to soluble activity varies almost 30-fold in different tissues, with the highest ratio in brain. Membrane-bound activity varies twofold within brain. In view of their different localization and kinetic properties, it seems likely that the two forms of COMT have different functions in vivo.
mesh_terms: D000818:Animals; D001921:Brain / Q000201:enzymology*; D002394:Catechol O-Methyltransferase / Q000378:metabolism*; D002462:Cell Membrane / Q000201:enzymology; D007668:Kidney / Q000201:enzymology; D007700:Kinetics; D008099:Liver / Q000201:enzymology; D008297:Male; D009928:Organ Specificity; D051381:Rats; D011919:Rats, Inbred Strains; D014649:Vas Deferens / Q000201:enzymology
chemical_list: D002394:Catechol O-Methyltransferase