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 materi al. To further explore its subcellular distribution in plant and anima l cells, we have raised a polyclonal antibody, Rb27, directed towards a conserved region (EEFATEGTDRKDVFFY) of the gamma-tubulin molecule. I mmunoblotting of cell protein extracts with Rb27 reveals a polypeptide band of M(r) 49 kD in HeLa and a 58 kD band in Chlamydomonas. Althoug h these polypeptides are comparable in size to forms of gamma-tubulin detected previously in mammalian and plant protein extracts by other a ntibodies to gamma-tubulin, by immunofluorescence microscopy Rb27 give s 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 mat erial. Because of the similarities in the size of the polypeptides rec ognized by our and other gamma-tubulin antibodies, and a restricted co -localization with known microtubule-organizing centres in evolutionar ily distant organisms, we propose that Rb27 recognizes a novel conserv ed gamma-tubulin isotype.