Isolation and identification of myosin I from porcine aorta media smooth muscle.
A complex of 110-kDa heavy chain and calmodulin was isolated from porcine aorta media smooth muscle and identified as myosin I. The isolated myosin I consisted of equimolar amounts of 110-kDa heavy chain and calmodulin. The addition of exogenous calmodulin to the complex revealed that a maximum of two molecules of calmodulin could be bound to the heavy chain. Isolated complex bound to F-actin in an ATP-dependent manner and its Mg(2+)-ATPase activity was activated by F-actin. In addition, it bound to phospholipid, which is a characteristic property of myosin I. Calcium ions induced a structural change, which was revealed by a difference in the cleavage pattern and for rate of cleavage by alpha-chymotrypsin. This behavior was similar to that reported for brush border myosin I [L.M. Collins and A. Bretscher (1988) J. Cell. Biol. 106, 367-373]. Calcium-dependent structural change of a complex of 110-kDa heavy chain and calmodulin was found from its solubility change at various NaCl concentrations in the presence of ATP. A complex of 116-kDa heavy chain and calmodulin, possibly another type of myosin I, was also isolated. A polyclonal antibody against the complex of 110-kDa heavy chain and calmodulin did not recognize the 116-kDa heavy chain. This result suggests that at least two types of myosin Is may exist at the protein level in porcine aorta media smooth muscle.
Hasegawa
Y
Y
Department of Applied Chemistry, Muroran Institute of Technology, Hokkaido.
Kikuta
T
T
Okamoto
Y
Y
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001011:Aorta / Q000737:chemistry*; D002118:Calcium / Q000494:pharmacology; D002852:Chromatography, Ion Exchange; D004533:Egtazic Acid / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D008970:Molecular Weight; D009131:Muscle, Smooth, Vascular / Q000737:chemistry*; D009218:Myosins / Q000737:chemistry / Q000302:isolation & purification*; D010743:Phospholipids / Q000378:metabolism; D011487:Protein Conformation; D013552:Swine
D010743:Phospholipids; D004533:Egtazic Acid; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; D009218:Myosins; D002118:Calcium