Sandbox Reserved 930: Difference between revisions

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• S1 Mg-ADP state corresponding to the myosin detached state (1b7t)
• S1 Mg-ADP state corresponding to the myosin detached state (1b7t)


By comparing the available crystal structures of different myosin S1 unit isoforms, it enables us to understand the conformational changes within the motor domain depending on the nucleotide content in the active site. Here mainly the structure and function of MD relevant in the S1 Mg-ADP (pre power stroke) state will be discussed.
By comparing the available crystal structures of different myosin S1 unit isoforms, it enables us to understand the conformational changes within the motor domain depending on the nucleotide content in the active site. Here mainly the structure and function of MD relevant in the S1 Mg-ADP (pre power stroke) state will be discussed.
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==The subdomains of the motor domain==
==The subdomains of the motor domain==


(Fig 3)
The MD of S1 unit is most frequently described as consisting of 4 subdomains: the converter, the N-terminal subdomain, and upper and lower 50-kDa subdomains <ref>PMID: 10338210</ref>. They are linked together by 3 single-stranded joints termed the switch II (residue IIe-461 to Asn-470), the relay (residues Asn-489 to ASP-519), and SH1 helix (Cys-693 to Phe-707) <ref>PMID: 11016966</ref>(Fig. 3).  
 
https://www.uic.edu/classes/phyb/phyb516/BaranyUpdate4/Myosin/Myosin.html
 
The MD of S1 unit is most frequently described as consisting of 4 subdomains: the converter, the N-terminal subdomain, and upper and lower 50-kDa subdomains (ref 4). They are linked together by 3 single-stranded joints termed the switch II (residue IIe-461 to Asn-470), the relay (residues Asn-489 to ASP-519), and SH1 helix (Cys-693 to Phe-707).  
 
• Of the MD subdomains the converter has the greatest positional change during contractile cycle. Connection of the converter and the lever arm allows relatively small changes in the converter to be greatly amplified in the lever arm fig?


• Of the MD subdomains the converter has the greatest positional change during contractile cycle. Connection of the converter and the lever arm allows relatively small changes in the converter to be greatly amplified in the lever arm
•
• Upper 50-kDa subdomain and N-terminal subdomain form the nucleotide binding pocket
• Upper 50-kDa subdomain and N-terminal subdomain form the nucleotide binding pocket
•
• Lower and upper 50-kDa subdomains form the interface where actin can bind<ref>PMID: 11016966</ref> 


• Lower 50-kDa subdomain and converter form the interface where actin can bind
Conformational changes in the flexible joints coordinate rearrangements of these four MD subdomains enabling the transition between different myosin S1 unit state within actomyosin contractile cycle. During the actomyosin cycle the MD undergoes many conformational changes as it traduces ATP hydrolysis to mechanical work. The different conformational states of myosin are termed strong or weak actin-binding states <ref>PMID: 15184651</ref>.


Conformational changes in the flexible joints coordinate rearrangements of these four MD subdomains enabling the transition between different myosin S1 unit states within the actomyosin contractile cycle. During the actomyosin cycle the MD undergoes many conformational changes as it traduces ATP hydrolysis to mechanical work. The different conformational states of myosin are termed strong or weak actin-binding states.




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