A GAMMA-TUBULIN THAT ASSOCIATES SPECIFICALLY WITH CENTRIOLES IN HELA-CELLS AND THE BASAL BODY COMPLEX IN CHLAMYDOMONAS

gamma-Tubulin is a putative component of microtubule initiating material. To further explore its subcellular distribution in plant and animal cells, we have raised a polyclonal antibody, Rb27, directed towards a conserved region (EEFATEGTDRKDVFFY) of the gamma-tubulin molecule. Immunoblotting of cell protein extracts with Rb27 reveals a polypeptide band of M(r) 49 kD in HeLa and a 58 kD band in Chlamydomonas. Although these polypeptides are comparable in size to forms of gamma-tubulin detected previously in mammalian and plant protein extracts by other antibodies to gamma-tubulin, by immunofluorescence microscopy Rb27 gives localization patterns not previously seen. It localizes specifically with the centrioles in HeLa cells and with the basal body complex in Chlamydomonas. Other gamma-tubulin antibodies label pericentriolar material. Because of the similarities in the size of the polypeptides recognized by our and other gamma-tubulin antibodies, and a restricted co-localization with known microtubule-organizing centres in evolutionarily distant organisms, we propose that Rb27 recognizes a novel conserved gamma-tubulin isotype.