Sodium Dodecyl Sulfate Gel Electrophoresis Studies of Connectin-Like High Molecular Weight Proteins of Various Types of Vertebrate and Invertebrate Muscles1

Using an SDS gel electrophoresis method, connectin, very high molecular weight (approximately 10(6) dalton) protein, was detected in an SDS extract of whole tissues of various types of muscles of vertebrates and invertebrates. Connectin bands were clearly recognized in all the types of striated muscles (skeletal and cardiac) of the vertebrates examined: rabbit, chicken, turtle, snake, newt, frog, and fish. This was also the case with skeletal muscle of prochordate, Amphioxus. In invertebrates, the situation was much complicated. Connectin-like protein bands were detected in C. elegans (nematode), but not in earthworm (annelid). Smaller sizes of proteins (approximately 10(6)) were faintly found in molluscan adductor muscles. In arthropods, connectin-like proteins were clearly detected in some muscles (e.g., claw muscles of crab and crayfish; leg muscles of several insects) but not at all in other muscles (e.g., tail muscles of crayfish and shrimp; thoracic muscles of some insects). These peculiar observations might be related to the presence of such specific elastic proteins as projectin in honeybee flight muscle. The present study has revealed that connectin is an elastic protein of vertebrate striated muscle, skeletal and cardiac muscles.