J. Biol. Chem., Vol. 258, Issue 4, 2163-2167, Feb, 1983
Identification of endorphin acetyltransferase in rat brain and pituitary gland
TL O'Donohue
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.