1dtl
CRYSTAL STRUCTURE OF CALCIUM-SATURATED (3CA2+) CARDIAC TROPONIN C COMPLEXED WITH THE CALCIUM SENSITIZER BEPRIDIL AT 2.15 A RESOLUTIONCRYSTAL STRUCTURE OF CALCIUM-SATURATED (3CA2+) CARDIAC TROPONIN C COMPLEXED WITH THE CALCIUM SENSITIZER BEPRIDIL AT 2.15 A RESOLUTION
Structural highlights
FunctionTNNC1_CHICK Troponin is the central regulatory protein of striated muscle contraction. Tn consists of three components: Tn-I which is the inhibitor of actomyosin ATPase, Tn-T which contains the binding site for tropomyosin and Tn-C. The binding of calcium to Tn-C abolishes the inhibitory action of Tn on actin filaments. Evolutionary Conservation![]() Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedCardiac troponin C (cTnC) is the calcium-dependent switch for contraction in heart muscle and a potential target for drugs in the therapy of congestive heart failure. This calmodulin-like protein consists of two lobes connected by a central linker; each lobe contains two EF-hand domains. The regulatory N-terminal lobe of cTnC, unlike that of skeletal troponin C (sTnC), contains only one functional EF-hand and does not open fully upon the binding of Ca(2+). We have determined the crystal structure of cTnC, with three bound Ca(2+) ions, complexed with the calcium-sensitizer bepridil, to 2.15-A resolution. In contrast to apo- and 3Ca(2+)-cTnC, the drug-bound complex displays a fully open N-terminal lobe similar to the N-terminal lobes of 4Ca(2+)-sTnC and cTnC bound to a C-terminal fragment of cardiac troponin I (residues 147-163). The closing of the lobe is sterically hindered by one of the three bound bepridils. Our results provide a structural basis for the Ca(2+)-sensitizing effect of bepridil and reveal the details of a distinctive two-stage mechanism for Ca(2+) regulation by troponin C in cardiac muscle. Bepridil opens the regulatory N-terminal lobe of cardiac troponin C.,Li Y, Love ML, Putkey JA, Cohen C Proc Natl Acad Sci U S A. 2000 May 9;97(10):5140-5. PMID:10792039[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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