Inner arm dynein ATPase fraction of sea urchin sperm flagella causes active sliding of axonemal outer doublet microtubule.

In order to clarify the role of the inner arms of the axoneme in sperm flagellar movement, we prepared an ATPase fraction (12S) from the outer arm-depleted axonemes of sea urchin sperm flagella. When both arm-depleted axonemes were incubated with the 12S ATPase, they exhibited the sliding disintegration of outer doublet microtubules. Electron microscopy revealed that the ATPase rebound to the original inner arm sites of the axoneme. Therefore, it is quite likely that the 12S ATPase is one of the components of the inner arms. We referred to it as "inner arm dynein".