title: Contents of myofibrillar proteins in cardiac, skeletal, and smooth muscles.
abstract: The in situ contents of myosin, actin, alpha-actinin, tropomyosin, troponin, desmin were estimated in dog cardiac, rabbit skeletal, and chicken smooth muscles. Whole muscle tissues were dissolved with 8 M guanidine hydrochloride and subjected to two-dimensional gel electrophoresis, which is a nonequilibrium pH gradient electrophoresis (Murakami, U. & Uchida, K. (1984) J. Biochem. 95, 1577-1584) with some modification. The amount of protein in a spot on a slab gel was determined by quantification of the extracted dye. Dye binding capacity of individual myofibrillar proteins was determined by using the purified protein. Myosin contents were 82 +/- 7 pmol/mg wet weight in cardiac muscle, 105 +/- 10 pmol/mg wet weight in skeletal muscle, and 45 +/- 4 pmol/mg wet weight in smooth muscle. Actin contents were 339 +/- 15 pmol/mg wet weight in cardiac muscle, 625 +/- 27 pmol/mg wet weight in skeletal muscle, and 742 +/- 13 pmol/mg wet weight in smooth muscle. The subunit stoichiometry of myosin in the three types of muscles was two heavy chains and four light chains, and there was one light chain 2 for every heavy chain. The molar ratio of actin to tropomyosin was 7/1 in the three types of muscles. Striking differences were seen in the molar ratio of myosin to actin: 1.0/4.1 in cardiac muscle, 1.0/6.0 in skeletal muscle, and 1.0/16.5 in smooth muscle.
mesh_terms: D000185:Actinin / Q000032:analysis; D000199:Actins / Q000032:analysis; D000818:Animals; D002147:Calmodulin / Q000032:analysis; D002645:Chickens; D003598:Cytoskeletal Proteins / Q000032:analysis*; D003893:Desmin / Q000032:analysis; D004285:Dogs; D007526:Isoelectric Point; D008970:Molecular Weight; D009124:Muscle Proteins / Q000032:analysis*; D009130:Muscle, Smooth / Q000032:analysis; D009132:Muscles / Q000032:analysis*; D009206:Myocardium / Q000032:analysis; D009218:Myosins / Q000032:analysis; D011817:Rabbits; D014335:Tropomyosin / Q000032:analysis; D014336:Troponin / Q000032:analysis
chemical_list: D000199:Actins; D002147:Calmodulin; D003598:Cytoskeletal Proteins; D003893:Desmin; D009124:Muscle Proteins; D014335:Tropomyosin; D014336:Troponin; D000185:Actinin; D009218:Myosins