Interaction between calponin and smooth muscle myosin.
Calponin is a thin filament-associated protein in smooth muscle that has been shown to bind actin, tropomyosin and calmodulin, and has been implicated to play a role in regulation of smooth muscle contractility. Using a centrifugation assay we found that calponin interacts with unphosphorylated filamentous smooth muscle myosin. We found that this calponin-myosin interaction is reversed by Ca(2+)-CaM, and depends on ionic strength. At 50 mM NaCl the binding constant and the stoichiometry of this interaction were estimated to be 2 x 10(6) M-1, and 1.2-2.4 calponin per myosin, respectively. We suggest that the calponin-myosin interaction could be involved in regulation of smooth muscle contractility by anchoring myosin to actin.
Szymanski
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PT
Department of Muscle Research, Boston Biomedical Research Institute, Boston, MA 02114.
Tao
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D000818:Animals; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D002417:Cattle; D002498:Centrifugation; D002645:Chickens; D008840:Microfilament Proteins; D009124:Muscle Proteins / Q000378:metabolism*; D009130:Muscle, Smooth / Q000378:metabolism*; D009218:Myosins / Q000378:metabolism*; D011485:Protein Binding; D011817:Rabbits; D011994:Recombinant Proteins / Q000378:metabolism; D012965:Sodium Chloride / Q000378:metabolism; D000096985:Calponins
D002135:Calcium-Binding Proteins; D008840:Microfilament Proteins; D009124:Muscle Proteins; D009218:Myosins; D011994:Recombinant Proteins; D012965:Sodium Chloride; D000096985:Calponins