Brain tubulin polymerization in the absence of "microtubule-associated proteins".

Pure tubulin dimer, purified by phosphecellulose chromatography to remove microtubule associated proteins, can be assembled into microtubules in the presence of dimethyl sulfoxide. The surfaces of such microtubules are devoid of filamentous material. The reaction is rapid and strongly dependent on protein concentration. No microtubule formation occurs from the purified tubulin when dimethyl sulfoxide is omitted.