Coupling between ATP hydrolysis and microtubule movement was demonstrated several years ago in flagellar axonemes1,2 and subsequent studies suggest that the relevant microtubule motor, dynein, uses ATP to drive microtubule sliding by a cross-bridge mechanism analogous to that of myosin in muscles3,4. Kinesin5, a microtubule-based motility protein which may participate in organelle transport and mitosis6, binds microtubules in a nucleo-tide-sensitive manner5,7,8, and requires hydrolysable nucleotides to translocate microtubules over a glass surface 9,10. Recently, neuronal kinesin was shown to possess microtubule-activated ATPase activity11,12 although coupling between ATP hydrolysis and motility was not demonstrated. Here we report that sea urchin egg kinesin, prepared either with or without a 5′-adenylyl imido-diphosphate(AMPPNP)-induced microtubule binding step, also possesses significant microtubule-activated ATPase activity when Mg-ATP is used as a substrate. This ATPase activity is inhibited in a dose-dependent manner by addition of Mg-free ATP, by chelation of Mg2+ with EDTA, by addition of Na3VO4, or by addition of AMPPNP with or without Mg2+ Addition of these same reagents also inhibits the microtubule-translocating activities of sea urchin egg kinesin in a dose-dependent manner, supporting the hypothesis that kinesin-driven motility is coupled to the microtubule-activated Mg2+-ATPase activity.
|Original language||English (US)|
|Number of pages||4|
|State||Published - 1988|
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