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| [[Image:1nkn.gif|left|200px]] | | {{Seed}} |
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| {{STRUCTURE_1nkn| PDB=1nkn | SCENE= }} | | {{STRUCTURE_1nkn| PDB=1nkn | SCENE= }} |
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| '''VISUALIZING AN UNSTABLE COILED COIL: THE CRYSTAL STRUCTURE OF AN N-TERMINAL SEGMENT OF THE SCALLOP MYOSIN ROD'''
| | ===VISUALIZING AN UNSTABLE COILED COIL: THE CRYSTAL STRUCTURE OF AN N-TERMINAL SEGMENT OF THE SCALLOP MYOSIN ROD=== |
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| ==Overview==
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| Alpha-helical coiled coils in muscle exemplify simplicity and economy of protein design: small variations in sequence lead to remarkable diversity in cellular functions. Myosin II is the key protein in muscle contraction, and the molecule's two-chain alpha-helical coiled-coil rod region--towards the carboxy terminus of the heavy chain--has unusual structural and dynamic features. The amino-terminal subfragment-2 (S2) domains of the rods can swing out from the thick filament backbone at a hinge in the coiled coil, allowing the two myosin 'heads' and their motor domains to interact with actin and generate tension. Most of the S2 rod appears to be a flexible coiled coil, but studies suggest that the structure at the N-terminal region is unstable, and unwinding or bending of the alpha-helices near the head-rod junction seems necessary for many of myosin's functional properties. Here we show the physical basis of a particularly weak coiled-coil segment by determining the 2.5-A-resolution crystal structure of a leucine-zipper-stabilized fragment of the scallop striated-muscle myosin rod adjacent to the head-rod junction. The N-terminal 14 residues are poorly ordered; the rest of the S2 segment forms a flexible coiled coil with poorly packed core residues. The unusual absence of interhelical salt bridges here exposes apolar core atoms to solvent.
| | The line below this paragraph, {{ABSTRACT_PUBMED_12867988}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 12867988 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_12867988}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Alpha helix]] | | [[Category: Alpha helix]] |
| [[Category: Coiled coil]] | | [[Category: Coiled coil]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 02:38:43 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 29 06:19:46 2008'' |
