title: The C-proteins of rabbit red, white, and cardiac muscles.
abstract: C-proteins have been isolated from rabbit red skeletal muscle (soleus and semitendinosus) and cardiac muscle and their structure and properties compared with those of white muscle C-protein. The Mr of white, red, and cardiac C-proteins are 135,000, 145,000, and 150,000, respectively, and their s20,w values are 4.3, 3.8, and 4.8 S, indicating that red C-protein is more asymmetric than the other two. They elute quite differently from hydroxylapatite columns. Two-dimensional CNBr peptide maps show extensive differences in primary structure, and anti-white C-protein does not precipitate red or cardiac C-protein. Despite these structural differences, all three C-proteins bind equally to white, red, or cardiac myosin and to actin. All three have the same effects on actomyosin ATPase in 50 mM KCl; they inhibit red and white skeletal actomyosins but slightly activate cardiac actomyosin. X-protein, a 140,000-dalton contaminant of white C-protein, was also investigated. It is very similar to red C-protein in elution from hydroxylapatite columns, S20,w, amino acid composition, and primary structure, but small differences in Mr and peptide maps indicate that the two proteins are probably not identical.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002352:Carrier Proteins / Q000302:isolation & purification* / Q000378:metabolism; D007700:Kinetics; D008970:Molecular Weight; D009130:Muscle, Smooth / Q000032:analysis; D009132:Muscles / Q000032:analysis*; D009206:Myocardium / Q000032:analysis*; D009218:Myosins / Q000378:metabolism; D009928:Organ Specificity; D010446:Peptide Fragments / Q000032:analysis; D011485:Protein Binding; D011817:Rabbits
chemical_list: D000596:Amino Acids; D002352:Carrier Proteins; D010446:Peptide Fragments; C020723:citrate-binding transport protein; D009218:Myosins