Acetylcholine synthesis in synaptosomes: mode of transfer of mitochondrial acetyl coenzyme A.
Labeled acetylcholine derived from labeled pyruvate in a synaptosomal preparation from rat brain, incubated with nicotinamide adenine dinucleotide as well as coenzyme A, is stimulated by calcium ions in the absence but not in the presence of Triton X-100. Whereas citrate is taken up by cholinergic synaptosomes because it suppresses the formation of acetylcholine from pyruvate, it is not itself converted into acetylcholine. The evidence suggests that there is a calcium-dependent transfer of mitochondrial acetyl coenzyme A into the cholinergic synaptoplasm, which is apparently devoid of the citrate cleavage enzyme, and is there converted into acetylcholine. The permeability of the inner mitochondrial membrane to coenzyme A and acetyl coenzyme A seems to be enhanced by calcium ions, and this effect may be mediated by mitochondrial phospholipase A2.
D001275:ATP Citrate (pro-S)-Lyase / Q000378:metabolism; D000105:Acetyl Coenzyme A / Q000378:metabolism*; D000109:Acetylcholine / Q000096:biosynthesis*; D000818:Animals; D001921:Brain / Q000378:metabolism*; D002118:Calcium / Q000502:physiology; D002951:Citrates / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism*; D009243:NAD / Q000378:metabolism; D010741:Phospholipases A / Q000378:metabolism; D054467:Phospholipases A2; D051381:Rats; D013574:Synaptosomes / Q000378:metabolism*
D002951:Citrates; D009243:NAD; D000105:Acetyl Coenzyme A; D001275:ATP Citrate (pro-S)-Lyase; D010741:Phospholipases A; D054467:Phospholipases A2; D000109:Acetylcholine; D002118:Calcium