Calcium-dependent control of caldesmon-actin interaction by S100 protein.
Caldesmon from chicken gizzard muscle has been examined for ability to interact with S100 protein using sedimentation, low-shear viscosity, and affinity chromatography. Ca2+/S100 protein, like Ca2+/calmodulin, inhibited the binding of caldesmon to F-actin in a concentration-dependent manner and the inhibition was not observed in the absence of Ca2+. Caldesmon was bound to S100 protein-Sepharose in the presence of Ca2+ and released with EGTA, indicating that there is a direct interaction between caldesmon and S100 protein. The binding of S100 protein to caldesmon also relieved actomyosin Mg2(+)-ATPase inhibition by caldesmon. The molar ratio of S100 protein to caldesmon required for half-maximal restoration was about 0.3, a value less than that in the case of calmodulin. S100 protein, however, was less effective in terms of the maximal extent of the restoration. With respect to Ca2(+)-sensitivity, the restoration profiles were monophasic with a midpoint at 3 x 10(-5) M for S100 protein and 8 x 10(-6) M for calmodulin. The restoration by S100 protein was almost wholly inhibited by TFP, but not by W-7. Taken together, our results suggest that a Ca2(+)-binding protein other than calmodulin may regulate caldesmon-dependent cellular functions.
Fujii
T
T
Department of Functional Polymer Science, Faculty of Textile Science and Technology, Shinshu University, Nagano.
Machino
K
K
Andoh
H
H
Satoh
T
T
Kondo
Y
Y
D000199:Actins / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002148:Calmodulin-Binding Proteins / Q000378:metabolism*; D002645:Chickens; D008970:Molecular Weight; D009218:Myosins / Q000378:metabolism; D011485:Protein Binding; D011817:Rabbits; D009418:S100 Proteins / Q000378:metabolism*; D013552:Swine
D000199:Actins; D002148:Calmodulin-Binding Proteins; D009418:S100 Proteins; D009218:Myosins; D002118:Calcium