Molecular forms of acetylcholinesterase in synaptic and extrasynaptic regions of avian tonic muscle.
Molecular forms of acetylcholinesterase and pseudocholinesterase were analyzed directly in the micro-dissected individual endplates of a slow-tonic chicken muscle. The major form in the endplate is the L2(6.5 S) form, while the collagen-tailed H2c (20 S) form, normally considered to be the synaptic form, is a very minor component, in contrast to its predominance at the chicken fast-twitch fibre endplate. The same is true for pseudocholinesterase at these endplates. Outside the tonic fibre endplates the same forms occur as at the endplates, but at a very much lower concentration. The enzyme at the tonic fibre endplate cannot be attached to the basal lamina by a collagen tail, but appears to have a hydrophobic attachment. Acetylcholinesterase is functional at tonic fibre endplates, but the absence of the collagen-tailed form may account for the lower efficiency of the enzymic removal of acetylcholine there.
D000110:Acetylcholinesterase / Q000032:analysis*; D000818:Animals; D002091:Butyrylcholinesterase / Q000032:analysis*; D002645:Chickens; D002802:Cholinesterases / Q000032:analysis*; D007527:Isoenzymes / Q000032:analysis*; D009045:Motor Endplate / Q000201:enzymology*; D009132:Muscles / Q000201:enzymology* / Q000294:innervation; D009469:Neuromuscular Junction / Q000201:enzymology*
D007527:Isoenzymes; D000110:Acetylcholinesterase; D002091:Butyrylcholinesterase; D002802:Cholinesterases