Heat-stable microtubule protein MAP-1 binds to microtubules and induces microtubule assembly.

The microtubule-associated proteins, MAP-1, MAP-2 and tau, have been purified from brain tissue via a new approach using a heating step directly on the homogenate, followed by selective adsorption on calmodulin-Sepharose affinity columns and gel-filtration chromatography. Our results indicate that these MAPs share common biochemical properties, including heat stability, calmodulin binding and promotion of tubulin assembly into microtubules.