Connectin content in rabbit cardiac and skeletal muscle

1. The contents of connectin in rabbit cardiac and skeletal muscle were estimated by densitometry of the bands in SDS gel electrophoresis. 2. The weight ratio of connectin to myosin was 1:9.5 in cardiac muscle and 1:4.2 in skeletal muscle. 3. Assuming that the molecular weights of myosin and skeletal muscle connectin were 5.25 x 10(5) and 4.2 x 10(6) respectively, and a myosin filament consists of 300 myosin molecules, it was calculated that there were approx. 4 connectin molecules per half of myosin filament in rabbit skeletal muscle. 4. In cardiac muscle, the molecular weight of connectin was assumed to be 3.6 x 10(6) and it was estimated that there were about 2 connectin filaments per half of myosin filament.