Jedrzejczyk_1984_Neurosci.Lett_46_283

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.