A MAJOR PORTION OF SYNAPTIC BASAL LAMINA ACETYLCHOLINESTERASE IS DETACHED BY HIGH SALT-CONTAINING AND HEPARIN-CONTAINING BUFFERS FROM RAT DIAPHRAGM MUSCLE AND TORPEDO ELECTRIC ORGAN

Collagen-tailed asymmetric acetylcholinesterase (AChE) forms are belie ved to be anchored to the synaptic basal lamina via electrostatic: int eractions involving proteoglycans. However, it was recently found that in avian and rat muscles, high ionic strength or polyanionic buffers could not detach AChE: from cell-surface clusters and that these buffe rs solubilized intracellular non-junctional asymmetric AChE rather tha n synaptic: forms of the enzyme. In the present study, asymmetric AChE forms were specifically solubilized by ionic buffers from sg synaptic basal! lamina-enriched fractions, largely devoid of intracellular mat erial, obtained from the electric organ of Torpedo californica and the end plate regions of rat diaphragm muscle, Furthermore, foci of AChE activity were seen to diminish in size, number, and staining intensity when the rat synaptic basal lamina-enriched preparations were treated with the extraction buffers, Pn the case of Torpedo, almost all the A ChE activity was removed from the pure basal lamina sheets. We therefo re conclude that a major portion of extracellular collagen-tailed AChE is extractable from rat and Torpedo synaptic basal lamina by high ion ic strength and heparin buffers,;although some non-extractable AChE ac tivity remains associated with the junctional regions.