Sandbox Reserved 930: Difference between revisions
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The MD has different conformational states in each step of the contractile cycle. The conformation of the MD in each state depends on which nucleotide is bound to the active site (if any). In each structural state the conformation of the MD changes relatively little, but these changes are enough to cause a substantial difference in the position of the lever arm (Fig. 4) <ref>PMID: 11016966</ref>. | The MD has different conformational states in each step of the contractile cycle. The conformation of the MD in each state depends on which nucleotide is bound to the active site (if any). In each structural state the conformation of the MD changes relatively little, but these changes are enough to cause a substantial difference in the position of the lever arm (Fig. 4) <ref>PMID: 11016966</ref>. | ||
The 50-kDa upper and lower subdomains as well as the converter control the motor function of the myosin head by rotating around the N-terminal subdomain. The rotations depend on the conformational changes of the 3 joints; switch II, SH1 helix region, and relay. <ref>PMID: 15184651</ref> The joints work together in the transition between the different conformational states of MD to control the overall organization of the myosin head. They also allow communication between the nucleotide-bonding pocket, acting-binding interface and the lever arm <ref>PMID: 11016966</ref>. | [[Image:Myosin turn.png|450px|right|thumb| Figure 5. Arrows in the upper figure show the direction of rotation of the 50-kDa lower and upper subdomains and the converter around the N-terminal subdomain. Lower picture shows the pivots around which SH1 unwinds. (Himmel 2002)]] | ||
The 50-kDa upper and lower subdomains as well as the converter control the motor function of the myosin head by rotating around the N-terminal subdomain (Fig 5). The rotations depend on the conformational changes of the 3 joints; switch II, SH1 helix region, and relay. <ref>PMID: 15184651</ref> The joints work together in the transition between the different conformational states of MD to control the overall organization of the myosin head. They also allow communication between the nucleotide-bonding pocket, acting-binding interface and the lever arm <ref>PMID: 11016966</ref>. | |||
Switch II, a catalytic loop of the nucleotide-binding pocket, moves in and out of the nucleotide-binding pocket during enzymatic activity. It is responsible for the unwinding of SH1 helix, along with the conformational changes caused by nucleotide binding. Upon unwinding helix SH1 uncouples the converter/lever module from the MD. <ref>PMID: 12297624</ref> Movement of the converter is controlled by the relay joint. The converter/relay module attains different conformations changing the position of the lever arm and thus giving rise to the different states of the actomyosin cycle <ref>PMID: 11016966</ref>. | Switch II, a catalytic loop of the nucleotide-binding pocket, moves in and out of the nucleotide-binding pocket during enzymatic activity. It is responsible for the unwinding of SH1 helix, along with the conformational changes caused by nucleotide binding. Upon unwinding helix SH1 uncouples the converter/lever module from the MD. <ref>PMID: 12297624</ref> Movement of the converter is controlled by the relay joint. The converter/relay module attains different conformations changing the position of the lever arm and thus giving rise to the different states of the actomyosin cycle <ref>PMID: 11016966</ref>. | ||
