A novel troponin T-like protein (calponin) in vascular smooth muscle: interaction with tropomyosin paracrystals.
Calponin is a smooth muscle tropomyosin-binding protein which is antigenically related to troponin T. The fine localization of calponin and troponin T on the polar paracrystals of smooth muscle tropomyosin were studied by electron microscopy. Both calponin and troponin T bound to the filamentous tropomyosin at a site about 17 nm away from the C-terminal end of tropomyosin molecule. This calponin-binding site corresponds to the domain which is highly conserved in the amino-acid sequences among the tropomyosin isoforms from skeletal muscle and smooth muscle. The result suggests that calponin, in collaboration with tropomyosin, may play an important role in regulating contractile apparatus.
Takahashi
K
K
Second Department of Internal Medicine, Ehime University School of Medicine, Japan.
Abe
M
M
Hiwada
K
K
Kokubu
T
T
D000818:Animals; D002135:Calcium-Binding Proteins / Q000502:physiology / Q000648:ultrastructure*; D003461:Crystallography; D003598:Cytoskeletal Proteins / Q000502:physiology; D066298:In Vitro Techniques; D046911:Macromolecular Substances; D008840:Microfilament Proteins; D008854:Microscopy, Electron; D009119:Muscle Contraction; D009131:Muscle, Smooth, Vascular / Q000502:physiology*; D011485:Protein Binding; D014335:Tropomyosin / Q000502:physiology / Q000648:ultrastructure*; D014336:Troponin / Q000648:ultrastructure; D020107:Troponin T; D000096985:Calponins
D002135:Calcium-Binding Proteins; D003598:Cytoskeletal Proteins; D046911:Macromolecular Substances; D008840:Microfilament Proteins; D014335:Tropomyosin; D014336:Troponin; D020107:Troponin T; D000096985:Calponins