Interaction of calponin with phospholipids.
The interaction between chicken gizzard calponin and phospholipids was examined by sedimentation assay and affinity chromatography. Calponin was sedimented with phosphatidylserine (PS) and phosphatidylinositol (PI) vesicles but not with phosphatidylcholine (PC) vesicles. The apparent Kd values of calponin to PS and PI were calculated to be 1.3 x 10(6) and 1.5 x 10(6) M-1, respectively. Domain mapping with chymotryptic digestion showed that the phospholipid-binding site resided within the N-terminal 22-kDa fragment, in which the bindings of actin, calmodulin, S100, and tropomyosin also occur. The amount of calponin bound to PS and PI vesicles decreased with increasing ionic strength or Ca2+ concentrations. The presence of MgCl2 was needed for the calponin-PS vesicle interaction. Calponin-binding proteins including actin, calmodulin, and S100 inhibited calponin binding to the phospholipid vesicles in a concentration-dependent manner, while tropomyosin had little effect on the binding. The inhibitory effects of calmodulin and S100 were found only in the presence of CaCl2. Neither caldesmon nor SM22 affected the binding.
Fujii
T
T
Department of Functional Polymer Science, Faculty of Textile Science and Technology, Shinshu University, Nagano.
Yamana
K
K
Ogoma
Y
Y
Kondo
Y
Y
D000199:Actins / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D002122:Calcium Chloride / Q000494:pharmacology; D002135:Calcium-Binding Proteins / Q000187:drug effects / Q000378:metabolism*; D002147:Calmodulin / Q000494:pharmacology; D002645:Chickens; D008081:Liposomes / Q000737:chemistry / Q000378:metabolism; D015636:Magnesium Chloride / Q000494:pharmacology; D008840:Microfilament Proteins; D008969:Molecular Sequence Data; D009124:Muscle Proteins / Q000494:pharmacology; D010716:Phosphatidylinositols / Q000737:chemistry / Q000378:metabolism; D010718:Phosphatidylserines / Q000737:chemistry / Q000378:metabolism; D010743:Phospholipids / Q000737:chemistry / Q000378:metabolism*; D011817:Rabbits; D012965:Sodium Chloride / Q000494:pharmacology; D013552:Swine; D014335:Tropomyosin / Q000494:pharmacology; D000096985:Calponins
D000199:Actins; D002122:Calcium Chloride; D002135:Calcium-Binding Proteins; D002147:Calmodulin; D008081:Liposomes; D015636:Magnesium Chloride; D008840:Microfilament Proteins; D009124:Muscle Proteins; D010716:Phosphatidylinositols; D010718:Phosphatidylserines; D010743:Phospholipids; D012965:Sodium Chloride; D014335:Tropomyosin; D000096985:Calponins