Sandbox 171: Difference between revisions

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MYOSIN


{{STRUCTURE_2mys|  PDB=2mys| Scene =Sandbox_171/Newscene/1'>active site }}
{{STRUCTURE_2mys|  PDB=2mys| Scene =Sandbox_171/Newscene/1'>active site }}
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[[Image:Myosin_head.gif|thumb|alt=Alt text|Myosin head]]
[[Image:Myosin_head.gif|thumb|alt=Alt text|Myosin head]]
[[Image:Myosin_chains.gif|thumb|alt=Alt text|Myosin filament]]
[[Image:Myosin_chains.gif|thumb|alt=Alt text|Myosin filament]]
Myosin has a molecular size of approximately 520 kilodaltons, with two 220 kD heavy chains and two pairs of light chains which vary in size.<ref name="Rayment" /> The molecule is asymmetric, having a long tail and two globular heads.  <ref name="Rayment" /> Each heavy chains composes the bulk of one of the globular heads.  <ref name="Rayment" /> Subfragment-1(S1) also termed the myosin head consists of ATP, actin, and two light chain binding sites.<ref name="Rayment" />  Each globular head has a heavy chain and two light chains for a combined molecular size of about 130 kD. <ref name="Rayment" />  
Myosin has a molecular size of approximately 520 kilodaltons with a total of six subunits.  It has two 220 kD heavy chains which make the majority of the overall structure and two pairs of light chains which vary in size.<ref name="Rayment" /> The molecule is asymmetric, having a long tail and two globular heads.  <ref name="Rayment" /> Each heavy chains composes the bulk of one of the globular heads.  <ref name="Rayment" /> Subfragment-1(S1) also termed the myosin head consists of ATP, actin, and two light chain binding sites.<ref name="Rayment" />  Each globular head has a heavy chain and two light chains for a combined molecular size of about 130 kD. <ref name="Rayment" />  


The myosin head is assymetrical with a length of 165 Angstroms and 65 Angstroms in width, with a total thickness of about 40 Angstroms. <ref name="Rayment" /> About 48% of the amino acid residues in the myosin head are dominated by α helices.  <ref name="Rayment" /> One long α helix of about 85 Angstroms stretches from the thick part of the myosin head to the COOH-terminus of the heavy chain. <ref name="Rayment" />  This particular helix forms the light chain binding region on the heavy chain. <ref name="Rayment" />
The myosin head is assymetrical with a length of 165 Angstroms and 65 Angstroms in width, with a total thickness of about 40 Angstroms. <ref name="Rayment" /> About 48% of the amino acid residues in the myosin head are dominated by α helices.  <ref name="Rayment" /> At the carboxyl terminus one long α helix of about 85 Angstroms extends in a left-handed coil. <ref name="Rayment" />  This particular helix forms the light chain binding region of the globular domain <ref name="Rayment" /> The amino terminus of each heavy chain has a large globular domain containing the site of ATP hydrolysis. 






==Function==
==Function==
 
Molecules of myosin aggregate in muscle cells to form thick filaments. <ref name="Lehninger">Nelson, D. and Cox, M.(2005). Lehninger Principles of Biochemistry. 4th ed. p.1119. </ref> 
Click the link to access DNAtube video "A Moving Myosin Motor Protein"
Click the link to access DNAtube video "A Moving Myosin Motor Protein"
http://www.dnatube.com/video/389/A-Moving-Myosin-Motor-Protein-myosin-actin-interaction
http://www.dnatube.com/video/389/A-Moving-Myosin-Motor-Protein-myosin-actin-interaction
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