PREPARATION OF A MONOCLONAL-ANTIBODY SPECIFIC FOR THE CLASS-I ISOTYPEOF BETA-TUBULIN - THE BETA-ISOTYPE OF TUBULIN DIFFER IN THEIR CELLULAR-DISTRIBUTIONS WITHIN HUMAN TISSUES

Tubulin, the subunit protein of microtubules, is an alpha/beta heterod imer. In many organisms, both alpha and beta consist of various isotyp es. Although the isotypes differ in their tissue distributions, the qu estion of whether the isotypes perform different functions in vivo is unanswered. In mammals, the beta(I) and beta(IV) isotypes are quite wi despread, and beta(II) is less so, while beta(III) and beta(VI) have n arrow distributions and beta(V) distribution is unknown. As a tool for localizing the isotypes, we report the preparation of a monoclonal an tibody specific for beta(I), to add to our previously described monocl onal antibodies specific for beta(II), beta(III), and beta(IV) [Banerj ee et al., J. Biol. Chem. 263:3029-3034, 1988; 265:1794-1799, 1990;267 :5625-5630, 1992]. In order to prepare this antibody, we have purified beta(I)-rich rat thymus tubulin. We have used our battery of antibodi es to localize the beta isotypes in four human tissues: oviduct, skin, colon, and pancreas. We have found striking differences in their tiss ue distributions. There is little or no beta(III) in these tissues, ex cept for the columnar epithelial cells of the colon. beta(II) is restr icted to very few cells, except in the skin, where it is concentrated in the stratum granulosum. beta(I) is widespread in all the epithelia. In the skin it is found in the entire stratum malpighii. In the ovidu ct, beta(I) is found largely in the nonciliated epithelial cells. In t he exocrine pancreas, beta(I) occurs only in the centroacinar cells an d not in the acinar cells; the latter do not stain with any of these a ntibodies. beta(IV) is present at very low levels in skin and pancreas . By contrast, it is prominent in the colon and also in the oviduct, w here it occurs in all the epithelial cells, especially in the ciliated cells, with the highest concentrations in the cilia themselves. These results suggest that the regulation of the expression and localizatio n of isotypes in tissues is very complex. (C) 1998 Wiley-Liss, Inc.