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
Oi. Casanueva et al., 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, The Journal of biological chemistry, 273(7), 1998, pp. 4258-4265
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.