Effect of 67 kDa calcimedin on caldesmon functioning.
Interaction of smooth muscle caldesmon with calmodulin, troponin C, S-100 protein and 67 kDa calcimedin was analyzed. Native gel electrophoresis and crosslinking revealed the complex formation between caldesmon and three EF-hand Ca-binding proteins, whereas calcimedin did not interact with caldesmon. In the presence of Ca2+, calcimedin binds to actin-tropomyosin without affecting the interaction of caldesmon with this complex. Although calcimedin reversed the inhibitory action of caldesmon on the actomyosin ATPase activity at a lower concentration than three other Ca-binding proteins, this effect only slightly depends on Ca2+ and was observed at the concentration of calcimedin comparable to that of actin. It is concluded that calcimedin itself cannot be responsible for Ca-dependent regulation of caldesmon functioning, but actin bundling induced by calcimedin (or by other actin binding proteins) decreases the inhibitory action of caldesmon on the actomyosin ATPase activity.
Bogatcheva
N V
NV
Department of Biochemistry, School of Biology, Moscow State University, Russian Federation.
Panaiotov
M P
MP
Vorotnikov
A V
AV
Gusev
N B
NB
D000199:Actins / Q000378:metabolism; D000818:Animals; D017302:Annexins / Q000378:metabolism / Q000502:physiology*; D002118:Calcium / Q000378:metabolism; D002147:Calmodulin / Q000378:metabolism; D002148:Calmodulin-Binding Proteins / Q000502:physiology*; D004372:Ducks; D009218:Myosins / Q000037:antagonists & inhibitors; D010743:Phospholipids / Q000378:metabolism; D009418:S100 Proteins / Q000378:metabolism; D014335:Tropomyosin / Q000378:metabolism
D000199:Actins; D017302:Annexins; D002147:Calmodulin; D002148:Calmodulin-Binding Proteins; D010743:Phospholipids; D009418:S100 Proteins; D014335:Tropomyosin; D009218:Myosins; D002118:Calcium