Tubulins from different higher plant species are immunologically nonidentical and bind colchicine differentially.
We have initiated immunological and drug-binding studies on the tubulins from different higher plant species. Antibodies were raised against electrophoretically separated rose (Rosa sp.) tubulin alpha- and beta-subunits and characterized by immunoblot autoradiographic assays. Each IgG preparation bound to its antigen and cross-reacted differentially with the respective tubulin subunits from an alga, sea urchin, rabbit, and cow. Antigenic determinants were shared more among the beta-subunits than among the alpha-subunits from these organisms. Tubulins were isolated from cultured cells of carrot (Daucus carota) and hibiscus (Hibiscus rosa-senensis). Immunoautoradiography and quantitation of cross-reactivity on blots showed nonidentity among homologous subunits from rose, carrot, hibiscus, and alga tubulins, with more antigenic differences among alpha-subunits than among beta-subunits. Comparative colchicine-binding assays showed that rose and hibiscus tubulins bound 33% and 65%, respectively, of the colchicine bound by carrot tubulin and that higher plant tubulins bound much less colchicine than bovine brain tubulin under identical conditions.
Morejohn
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Department of Developmental and Cell Biology, University of California, Irvine, CA 92717.
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