2k2a

Solution Structure of the Apo C terminal domain of Lethocerus troponin C isoform F1Solution Structure of the Apo C terminal domain of Lethocerus troponin C isoform F1

Structural highlights 2k2a is a 1 chain structure with sequence from Lethocerus indicus. Full experimental information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: Solution NMR Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function Q868D4_9HEMI 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 PubMed Muscle contraction is activated by two distinct mechanisms. One depends on the calcium influx, and the other is calcium-independent and activated by mechanical stress. A prototypical example of stretch activation is observed in insect muscles. In Lethocerus, a model system ideally suited for studying stretch activation, the two mechanisms seem to be under the control of different isoforms of troponin C (TnC), F1 and F2, which are responsible for stretch and calcium-dependent regulation, respectively. We have previously shown that F1 TnC is a typical collapsed dumbbell EF-hand protein that accommodates one calcium ion in its fourth EF-hand. When calcium loaded, the C-terminal domain of F1 TnC is in an open conformation which allows binding to troponin I. We have determined the solution structure of the isolated F1 TnC C-terminal domain in the absence of calcium and have compared it together with its dynamical properties with those of the calcium-loaded form. The domain is folded also in the absence of calcium and is in a closed conformation. Binding of a single calcium is sufficient to induce a modest but clear closed-to-open conformational transition and releases the conformational entropy observed in the calcium-free form. These results provide the first example of a TnC domain in which the presence of only one calcium ion is sufficient to induce a closed-to-open transition and clarify the role of calcium in stretch activation. Solution structure of the Apo C-terminal domain of the Lethocerus F1 troponin C isoform.,De Nicola GF, Martin S, Bullard B, Pastore A Biochemistry. 2010 Mar 2;49(8):1719-26. PMID:20104876 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Troponin 3D structures

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