Interaction of the cytoskeletal framework with acetylcholine receptor on the surface of embryonic muscle cells in culture

To monitor the interaction of cell surface acetylcholine (AcCho) receptors with the cytoskeleton, cultured muscle cells were labeled with radioactive or fluorescent α-bungarotoxin and extracted with Triton X-100, using conditions that preserve internal structure. A significant population of the AcCho receptors is retained on the skeletal framework remaining after detergent extraction. The proportion of nonextracted AcCho receptors increases during myotube development. Both photographic images and quantitative fluorescence measurements indicate that AcCho receptors in patched or aggregated areas are retained on the cytoskeleton while the diffuse receptors are partially extracted by detergent. The skeleton organization responsible for restricting AcCho receptors to a patched region may also result in their retention after detergent extraction.