Isolation of microtubule protein from mammalian brain frozen for extended periods of time.

Microtubule protein (MTP) may be isolated in good yield from frozen brains by cycles of temperature-dependent polymerization and depolymerization. If the brains are frozen quickly and stored at -70 degrees C, the yield of MTP is stable for a period of at least 2 months and the yield is only slightly decreased after nearly a year. Cow as well as rat brains may be stored in this manner, provided appropriate precautions are taken to ensure rapid freezing of the cow brain. This procedure allows brains to be accumulated over a period of time for MTP isolation at a convenient later date.