Supplementary Information For “ Mechanical coupling between myosin molecules causes differences between ensemble and single molecule measurements ”
Supplementary Information For “ Mechanical coupling between myosin molecules causes differences between ensemble and single molecule measurements ”
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发表时间：
2012
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通讯作者：
S. Walcott;D. Warshaw;E. Debold
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作者：
S. Walcott;D. Warshaw;E. Debold
我们考虑正文图1所示的肌动球蛋白相互作用的四态模型，并在下面复制(见图1)。简而言之，未结合(或弱结合)的肌球蛋白与其活性部位的ADP和磷酸(PI)转变为与肌动蛋白强结合的状态。我们将前一种状态(与活性部位的ADP和PI未结合/弱结合)标记为状态1，而将后一状态(与活性部位的ADP结合)标记为状态2。一旦强结合，肌球蛋白可能以力依赖的过程释放ADP。然后进入僵硬状态，状态3。在释放了ADP和磷酸盐后，肌球蛋白的核苷酸结合口袋是空的，分子可能会与ATP结合，一旦这样做，就会解除与肌动蛋白的结合。一旦结合了ATP，肌球蛋白从肌动蛋白中分离出来，肌球蛋白就可以水解ATP，恢复到PowerStroke前的构象，状态1(见图1)。
We consider the 4-state model for actomyosin interaction shown in Fig. 1 of the main text and reproduced here below (see Fig. 1). Briefly, unbound (or weakly-bound) myosin with ADP and phosphate (Pi) in its active site transitions to a state where it strongly binds to actin. We label the former state (un-/weaklybound with ADP and Pi in the active site) state 1, while the latter state (bound with ADP in the active site) is state 2. Once strongly bound, myosin may release ADP in a force-dependent process. It then enters the rigor state, state 3. Having released both ADP and phosphate, myosin’s nucleotide binding pocket is empty and the molecule may bind ATP, and upon doing so, unbind from actin. This unbound state with ATP in the active site is state 4. Once ATP is bound and myosin has detached from actin, myosin may hydrolyze ATP and revert to the pre-powerstroke conformation, state 1 (see Fig. 1).