Properties of calponin isolated from sheep aorta thin filaments.
Calponin, a 35 kDa actin-binding protein, was shown to be a normal component of 'native' thin filaments prepared from sheep aorta. Actin, tropomyosin, caldesmon and calponin were present in molar ratios 14:2:1:0.9. Calponin was isolated from thin filaments in yield 0.5 mg/100 mg thin filament protein. Calponin inhibited actomyosin ATPase up to 85%, half maximal at 0.2 calponin/actin. Inhibition did not depend on tropomyosin, Ca2+ or Ca2+ calmodulin. Caldesmon inhibited actomyosin with a 10-fold greater potency than calponin in the presence of tropomyosin and inhibition could be reversed by Ca2+ calmodulin under certain conditions. Calponin had no effect on caldesmon inhibition or the reversal of inhibition.
Marston
S B
SB
Department of Cardiac Medicine, National Heart and Lung Institute, London, UK.
D000818:Animals; D001011:Aorta / Q000737:chemistry*; D002135:Calcium-Binding Proteins / Q000302:isolation & purification / Q000378:metabolism*; D002148:Calmodulin-Binding Proteins / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D008840:Microfilament Proteins; D009124:Muscle Proteins / Q000302:isolation & purification / Q000378:metabolism*; D009218:Myosins / Q000037:antagonists & inhibitors; D012756:Sheep; D000096985:Calponins
D002135:Calcium-Binding Proteins; D002148:Calmodulin-Binding Proteins; D008840:Microfilament Proteins; D009124:Muscle Proteins; D009218:Myosins; D000096985:Calponins