Distribution and characteristics of betaII tubulin-enriched microtubules in interphase cells.

We have used a polyclonal antibody (Ab196) that specifically recognizes the betaII tubulin isotype to examine the subcellular distribution and properties of microtubules enriched in this isotype. Antibody specificity was tested by a method that involves the analysis of its interaction with individual beta isotypes. Using photoimaging analysis, we observed betaII tubulin-enriched microtubules in the perinuclear region, as well as in the microtubules close to the periphery of interphase cells. The observed sorting of betaII-enriched microtubules together with the reported increased levels of betaII tubulin in taxol-resistant cells (M. Haber et al., 1995, J. Biol. Chem. 270, 31269-31275) prompted us to study the behavior of microtubules enriched in this isotype after different depolymerizing treatments. After cold or nocodazol treatments, betaII-enriched microtubules anchored at the centrosome and at the cell periphery were observed. In addition, cold-resistant microtubules were marked mainly by the specific anti-betaII tubulin antibody but not by anti-acetylated alpha tubulin, suggesting the presence of different stable microtubule subsets enriched in particular tubulin isoforms. Copyright 1999 Academic Press.