Association of acetylcholinesterase with the external surface of the presynaptic plasma membrane in Torpedo electric organ.
A high acetylcholinesterase (AChE) activity was found associated with pure cholinergic synaptosomes prepared from Torpedo electric organ. This activity was bound to the presynaptic plasma membrane upon subfractionation on sucrose density gradients. It was not solubilized in the presence of 2 M MgCl(2) but in the presence of Triton X 100. This presynaptic AChE activity corresponded to a hydrophobic form of the enzyme with a sedimentation coefficient of 5.5 S in our conditions. More than 80% of the AChE activity of intact synaptosomes was externally oriented. The presynaptic AChE activity could represent as much as 25% of the total activity in Torpedo electric organ.
Morel
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N
Département Neurochimie, Lab. Neurobiologie Cellulaire, C.N.R.S., 91190 Gif sur Yvette, France.
Dreyfus
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P