1KQL

Crystal structure of the C-terminal region of striated muscle alpha-tropomyosin at 2.7 angstrom resolution

Summary for 1KQL

• Entry DOI: 10.2210/pdb1kql/pdb
• Descriptor: Fusion Protein of and striated muscle alpha-tropomyosin and the GCN4 leucine zipper (2 entities in total)
• Functional Keywords: thin filament, tropomyosin, muscle regulation, coiled coil, contractile protein, four-helix bundle
• Biological source: Saccharomyces cerevisiae (baker's yeast, Norway rat); More
• Total number of polymer chains: 2
• Total formula weight: 13206.96

Authors

Li, Y.,Mui, S.,Brown, J.H.,Strand, J.,Reshetnikova, L.,Tobacman, L.S.,Cohen, C. (deposition date: 2002-01-07, release date: 2002-05-29, Last modification date: 2024-04-03)

Primary citation

Li, Y.,Mui, S.,Brown, J.H.,Strand, J.,Reshetnikova, L.,Tobacman, L.S.,Cohen, C.
The crystal structure of the C-terminal fragment of striated-muscle alpha-tropomyosin reveals a key troponin T recognition site.
Proc.Natl.Acad.Sci.USA, 99:7378-7383, 2002

PubMed Abstract: 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.

PubMed: 12032291
DOI: 10.1073/pnas.102179999

Experimental method

X-RAY DIFFRACTION (2.7 Å)