GAMMA-TUBULIN REDISTRIBUTION IN TAXOL-TREATED MITOTIC CELLS PROBED BYMONOCLONAL-ANTIBODIES

Monoclonal antibodies were prepared against conserved synthetic peptid e from the C-terminus of the gamma-tubulin and their specificity was c onfirmed by immunoblotting, competitive enzyme-linked immunosorbent as say (ELISA) and immunofluorescence. The antibodies decorated interphas e centrosomes as well as half-spindles and midbodies in mitotic cells of various origin. The prepared antibodies were used to study the gamm a-tubulin distribution in nocodazole and taxol-treated cells. In the c ells recovering from the nocodazole treatment, gamma-tubulin was found in centers of all microtubule asters. Examination of relative locatio n of gamma-tubulin and microtubule asters in taxol-treated mitotic cel ls 3T3, HeLa and PtK2 revealed that the number of taxol-induced microt ubule asters exceeded the number of gamma-tubulin-positive spots. The gamma-tubulin was often found in the periphery of microtubule asters. Centrosomal phosphoprotein epitope detected by MPM-2 antibody colocali zed with gamma-tubulin in taxol-treated mitotic cells. The presented d ata suggest that taxol-induced microtubule asters are in vivo nucleate d independently of gamma-tubulin, and other minus-end nucleator(s) are necessary for formation of such asters. Alternatively, gamma-tubulin is present in subthreshold amounts undetectable by immunofluorescence. (C) 1996 Wiley-Liss, Inc.