Premium
Acetylation of Choline and Homocholine by Membrane‐Bound Choline‐ O ‐Acetyltransferase in Mouse Forebrain Nerve Endings
Author(s) -
Benishin C. G.,
Carroll P. T.
Publication year - 1981
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1981.tb01649.x
Subject(s) - choline acetyltransferase , free nerve ending , forebrain , choline , chemistry , acetylcholine , neuroscience , membrane , biophysics , anatomy , microbiology and biotechnology , biochemistry , cholinergic , biology , central nervous system , endocrinology
The choline analog homocholine is not acetylated in vitro by choline‐ O ‐acetyltransferase (ChAT, EC 2.3.1.6), which is solubilized by 100 mM‐sodium phosphate buffer washes of a crude vesicular fraction of mouse forebrain. However, both homocholine and choline are acetylated by a form of ChAT which is nonionically associated with a subcellular fraction of mouse forebrain containing membrane‐associated organelles and occluded acetylcho‐line (P 4 ). Acetylation of homocholine by membrane‐associated ChAT is saturable. 4‐(1‐Naphthylvinyl)pyridine (NVP) inhibits the acetylation of both choline (60%) and homocholine (40%) by membrane‐associated ChAT but reduces the acetylation of choline alone by soluble ChAT (76%). Choline and homocholine serve as competitive alternative substrates for the same membrane‐associated ChAT, whereas homocholine acts only as a competitive inhibitor of choline acetylation by soluble ChAT. Acetylhomocholine competitively inhibits the acetylation of choline by both soluble and membrane‐associated ChAT more dramatically than does the natural end product, acetylcholine.