Post-translational modification of tubulin in cultured neurons

Isoelectricfocusing x SDS polyacrylamide gel electrophoresis of cultured sympathetic neurons revealed two alpha- and two beta-subunits of tubulin. In pulse-chase experiments, the spot morphology of the beta-subunits synthesized during a 10 min pulse did not change appreciably during the chase period. However, the appearance of the labeled alpha-subunits changed during the chase period. With chase periods of less than 4 h, the labeled alpha-subunits focused as discrete spots, while after chase periods of greater than 6 h, they focused as short streaks.