Association of tailed acetylcholinesterase to lipidic membranes in mammalian skeletal muscle

Tailed acetylcholinesterase (AChE) was studied in three subcellular membrane fractions of mouse skeletal muscle: a fraction enriched in isolated motor endplates (C), an extrasynaptic membrane fraction (A) and a microsomal fraction (S). In the (C) fraction, tailed asymmetric 16S AChE required high salt conditions to be extracted, while in (A) and (S) microsomal membranes, a collagenase sensitive 16S form, was extracted by detergent alone. This apparent “hydrophobic” property suggests that there is a pool of 16S AChE which is probably bound to lipidic membranes. The detergent extractable (DE) 16S AChE was not concentrated in motor endplate-rich regions and differential inhibition of external and internal AChE demonstrated that it could have both intra- and extracellular locations in the adult differentiated muscle fibres.