Muscle surface membranes. Preparative methods affect apparent chemical properties and neurotoxin binding

摘要: Considerable disagreement exists between results reported by various authors for lipid composition and enzyme activity in purified muscle membrane fractions presumed to be sarcolemma, although an explanation these discrepancies has not been presented. We have prepared light surface of comparable density (1.050–1.120) a low-salt sucrose method LiBr-KCl extraction procedure compared them profile, total cholesterol content, protein ATPase activity. In addition, sodium channels characteristic excitable membranes quantitated each preparation using [3H]saxitoxin binding assays, the acetylcholine receptors determined from control denervated α-[125I]bungarotoxin. Although both contain predominantly membrane, LiBr fraction consistently shows higher specific p-nitrophenylphosphatase, free receptors. The distribution appears uniform throughout fractions. Quantitative differences were seen dodecyl sulfatepolyacrylamide gel electrophoresis patterns proteins two preparations most bands are represented both. A majority accessible varying degrees labelling with diazotized diiodosulfanylic acid intact muscle. These suggest that may mixtures sarcolemma T-tubular membranes. Using our preparative methods, while enriched elements.