On the Walking Mechanism of Linear Molecular Motors
Many of linear molecular motors, such as myosins and kinesins, have two “feet” (traditionally called “heads” or “motor domains”) that bind to a motor-specific track and that each host a catalytic site for hydrolyzing ATP to power unidirectional movement along the track (Kinosita et al., 1998, 2005; Vale and Milligan, 2000; Mehta, 2001; Endow and Barker, 2003; Schliwa and Woehlke, 2003; Vale, 2003; Sablin and Fletterick, 2004). Some of the linear motors, such as conventional kinesin (Brady, 1985; Vale et al., 1985; Howard et al., 1989; Block et al., 1990; Svoboda et al., 1993), myosin V (Cheney et al., 1993; Mehta et al., 1999; Sakamoto et al., 2000), myosin VI (Kellerman and Miller, 1992; Wells et al., 1999; Rock et al., 2001; Nishikawa et al., 2002), and plant myosin XI (Tominaga et al., 2003), are processive, in that a single motor molecule proceeds along a filamentous track for many ATPase cycles without detaching from the track. That the two feet never detach simultaneously from the track (or the ground in case of a human) is an important feature of “walking,” as opposed to “running” (Kinosita et al., 1998). In addition, at least for myosin V and conventional kinesin which are known to be processive, convincing evidence exists that these motors throw their two feet forward alternately in a hand-over-hand fashion (Yildiz et al., 2003, 2004; Asbury et al., 2003; Kaseda et al., 2003; Warshaw et al., 2005), just as a human does.
KeywordsLanding Site Molecular Motor Lever Action Coiled Coil Myosin Versus
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