A transient association of gamma-tubulin at the midbody is required for the completion of cytokinesis during the mammalian cell division.

gamma-Tubulin, a relatively new member of the tubulin gene family, is localized primarily at the centrosome throughout the mammalian cell cycle and may play a key role in nucleation of cellular microtubule assembly. A transient association of gamma-tubulin at the cytoplasmic bridge of telophase mammalian cells, the midbody, is recently documented. Using immunogold electron microscopy and serial section reconstruction analysis, we show here that the transiently associated midbody gamma-tubulin is localized at the minus ends of microtubules in the midbody structure. Using antisense RNA methods we also demonstrate that a selective depletion of transiently associated midbody gamma-tubulin causes an abortive cytokinesis due to a failure in the morphogenesis of the midbody structure.