Changes in the relative electrophoretic mobility of higher plant tubulin subunits in SDS-polyacrylamide gels

The relative electrophoretic mobility of higher plant tubulin subunits in SDS-polyacrylamide gels varies depending upon the electrophoretic methods used to separate them. When reduced and alkylated rat and carrot tubulin heterodimers were separated by one method, the α-tubulin subunits, identified by means of a highly specific antibody, migrated more slowly than the β-tubulin subunits. However, when separated by another method, the carrot α-subunit migrated more rapidly than its β-subunit, while the relative mobility of rat brain tubulin subunits was unchanged. The two gel systems differ principally in the pH of the separating gel during electrophoresis, suggesting that pH markedly influences the interaction of SDS with the plant, but not the vertebrate α-tubulin.