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Publication Abstract from PubMed

To gain a molecular description of how muscles can be activated by mechanical stretch, we have solved the structure of the calcium-loaded F1 isoform of troponin C (TnC) from Lethocerus and characterized its interactions with troponin I (TnI). We show that the presence of only one calcium cation in the fourth EF hand motif is sufficient to induce an open conformation in the C-terminal lobe of F1 TnC, in contrast with what is observed in vertebrate muscle. This lobe interacts in a calcium-independent way both with the N terminus of TnI and, with lower affinity, with a region of TnI equivalent to the switch and inhibitory peptides of vertebrate muscles. Using both synthetic peptides and recombinant proteins, we show that the N lobe of F1 TnC is not engaged in interactions with TnI, excluding a regulatory role of this domain. These findings provide insights into mechanically stimulated muscle contraction.

The structure of Lethocerus troponin C: insights into the mechanism of stretch activation in muscles.,De Nicola G, Burkart C, Qiu F, Agianian B, Labeit S, Martin S, Bullard B, Pastore A Structure. 2007 Jul;15(7):813-24. PMID:17637342^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.