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1kql
From Proteopedia
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Crystal structure of the C-terminal region of striated muscle alpha-tropomyosin at 2.7 angstrom resolution
Overview
Contraction in striated and cardiac muscles is regulated by the motions of, a Ca(2+)-sensitive tropomyosin/troponin switch. In contrast, troponin is, absent in other muscle types and in nonmuscle cells, and actomyosin, regulation is myosin-linked. Here we report an unusual crystal structure, at 2.7 A of the C-terminal 31 residues of rat striated-muscle, alpha-tropomyosin (preceded by a fragment of the GCN4 leucine zipper). The, C-terminal 22 residues (263-284) of the structure do not form a, two-stranded alpha-helical coiled coil as does the rest of the molecule, but here the alpha-helices splay apart and are stabilized by the formation, of a tail-to-tail dimer with a symmetry-related molecule. The site of, splaying involves a small group of destabilizing core residues that is, present only in striated muscle tropomyosin isoforms. These results reveal, a specific recognition site for troponin T and clarify the physical basis, for the unique regulatory mechanism of striated muscles.
About this Structure
1KQL is a Single protein structure of sequence from Saccharomyces cerevisiae and rattus norvegicus. Full crystallographic information is available from OCA.
Reference
The crystal structure of the C-terminal fragment of striated-muscle alpha-tropomyosin reveals a key troponin T recognition site., Li Y, Mui S, Brown JH, Strand J, Reshetnikova L, Tobacman LS, Cohen C, Proc Natl Acad Sci U S A. 2002 May 28;99(11):7378-83. PMID:12032291
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