Distribution and characteristics of beta II tubulin-enriched microtubules in interphase cells

We have used a polyclonal antibody (Ab196) that specifically recognizes the beta II tubulin isotype to examine the subcellular distribution and proper ties of microtubules enriched in this isotype. Antibody specificity was tes ted by a method that involves the analysis of its interaction with individu al beta isotypes. Using photoimaging analysis, we observed beta II tubulin- enriched microtubules in the perinuclear region, as well as in the microtub ules close to the periphery of interphase cells. The observed sorting of be ta II-enriched microtubules together with the reported increased levels of beta II tubulin in taxol-resistant cells (IM. Haber et al., 1995, J. Biol. Chem. 270, 31269-31275) prompted us to study the behavior of microtubules e nriched in this isotype after different depolymerizing treatments. After co ld or nocodazol treatments, beta II-enriched microtubules anchored at the c entrosome and at the cell periphery were observed. In addition, cold-resist ant microtubules were marked mainly by the specific anti-beta II tubulin an tibody but not by anti-acetylated alpha tubulin, suggesting the presence of different stable microtubule subsets enriched in particular tubulin isofor ms. (C) 1999 Academic Press.