Tubulin aggregates induced by Ni2+ present microtubular characteristics

Rat brain tubulin in a proper buffered solution became insoluble in the presence of 10 mM NiCl2, and sedimented at centrifugal forces as low as 500 x g for 30 min. Both nickel-sedimented and microtubular tubulin conserved 65% of colchicine binding activity after 25 days of storage at -20 degrees C. However in brain cytosol, only 9% of the initial binding activity was conserved. The electrophoretic mobility of tubulin recovered from aggregates also remained unaltered. Therefore the aggregates formed with Ni2+ share important physicochemical properties with microtubules.