Centrosomes nucleate microtubules and serve as poles of the mitotic spindle. Centrioles are a core component of centrosomes and duplicate once per cell cycle. We previously identified -tubulin as a new member of the tubulin superfamily that localizes asymmetrically to the two centrosomes after duplication. We show that recruitment of -tubulin to the new centrosome can only occur after exit from S phase and that -tubulin is associated with the sub-distal appendages of mature centrioles. Xenopus laevis-tubulin was cloned and shown to be similar to human -tubulin in both sequence and localization. Depletion of -tubulin from Xenopus egg extracts blocks centriole duplication in S phase and formation of organized centrosome-independent microtubule asters in M phase. We conclude that -tubulin is a component of the sub-distal appendages of the centriole, explaining its asymmetric localization to old and new centrosomes, and that -tubulin is required for centriole duplication and organization of the pericentriolar material.
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-Tubulin is required for centriole duplication and microtubule organization
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