Identification of endorphin acetyltransferase in rat brain and pituitary gland.
An enzyme which N-acetylates beta-endorphin has been identified and characterized in the rat brain and pituitary gland. The beta-endorphin acetyltransferase activity was localized almost exclusively in the intermediate lobe of the pituitary gland. beta-endorphin acetyltransferase activity was also present in the hypothalamus, a brain region which synthesizes beta-endorphin, but not the cerebellum, a region which does not synthesize beta-endorphin. The substrate specificity of beta-endorphin acetyltransferase appeared to be located in the NH2 terminus and midportions of the beta-endorphin sequence. The regional distribution and pharmacological specificity of beta-endorphin acetyltransferase indicate that it is a highly specialized regulatory enzyme. Because N-acetyl-beta-endorphin is nonanalgesic and does not bind to the opiate receptor (Smyth, D.G., Massey, D.E., Zakarian, S., and Finnie, M.D. (1979) Nature (Lond.) 279, 252-254), it appears that the physiological significance of beta-endorphin acetyltransferase is that it can modulate the activity of endorphin secreted from opiomelanotropinergic cells and neurons.
D000123:Acetyltransferases / Q000378:metabolism*; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001921:Brain / Q000201:enzymology*; D002162:Camelus; D002851:Chromatography, High Pressure Liquid; D004723:Endorphins / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008297:Male; D063206:N-Terminal Acetyltransferases; D010902:Pituitary Gland / Q000201:enzymology*; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors; D014018:Tissue Distribution; D001615:beta-Endorphin
D000596:Amino Acids; D004723:Endorphins; D001615:beta-Endorphin; D000123:Acetyltransferases; D063206:N-Terminal Acetyltransferases