Plasma Membranes from Cultured Muscle Cells: Isolation Procedure and Separation of Putative Plasma-Membrane Marker Enzymes

摘要: Abstract Partially purified plasma membranes were obtained from chick-embryo muscle cells grown in tissue culture. The purification procedure involved homogenization buffered isotonic sucrose followed by differential and density gradient centrifugations. activities of five plasma-membrane markers, as well microsomal mitochondrial throughout the purification. When cultures labeled with [125I]α-bungarotoxin, which binds to surface cultured cells, distributions bound α-bungarotoxin Na+,K+-ATPase (EC 3.6.1.3) activity nearly identical. these two markers maximal upper fractions 5- 7-fold respect total particulate protein. These contained 20-30% α-bungarotoxin, 4% marker TPNH-dependent cytochrome c reductase, 0.2% succinate-dependent 2.7% cellular RNA, 0.02% DNA. commonly used marker, 5′-nucleotidase 3.1.3.5), was low a more dense fraction. other leucyl β-naphthylamidase phosphodiesterase I, intermediate between 5′-nucleotidase. all similar preparations containing mononucleated myogenic multinucleated myotubes, fibroblasts, or three cell types. Modification include absence resulted 3.4-fold 5′-nucleotidase, shifted lower density.