2b9c

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Template:STRUCTURE 2b9c

Structure of tropomyosin's mid-region: bending and binding sites for actin

Overview

Tropomyosin is a two-chain alpha-helical coiled coil whose periodic interactions with the F-actin helix are critical for thin filament stabilization and the regulation of muscle contraction. Here we deduce the mechanical and chemical basis of these interactions from the 2.3-A-resolution crystal structure of the middle three of tropomyosin's seven periods. Geometrically specific bends of the coiled coil, produced by clusters of core alanines, and variable bends about gaps in the core, produced by isolated alanines, occur along the molecule. The crystal packing is notable in signifying that the functionally important fifth period includes an especially favorable protein-binding site, comprising an unusual apolar patch on the surface together with surrounding charged residues. Based on these and other results, we have constructed a specific model of the thin filament, with the N-terminal halves of each period (i.e., the so-called "alpha zones") of tropomyosin axially aligned with subdomain 3 of each monomer in F-actin.

About this Structure

2B9C is a Single protein structure of sequence from Rattus norvegicus. Full crystallographic information is available from OCA.

Reference

Structure of the mid-region of tropomyosin: bending and binding sites for actin., Brown JH, Zhou Z, Reshetnikova L, Robinson H, Yammani RD, Tobacman LS, Cohen C, Proc Natl Acad Sci U S A. 2005 Dec 27;102(52):18878-83. Epub 2005 Dec 19. PMID:16365313 Page seeded by OCA on Sat May 3 20:00:44 2008