On the use of heat stability as a criterion for the identification of microtubule associated proteins (MAPs).

Solubility at elevated temperature is a striking biochemical property exhibited by a restricted number of the known microtubule associated proteins. This property has been extremely useful in the identification of these proteins and in their purification as well. It is reported here that heat stability is a function of the composition of proteins present during exposure to elevated temperature. All non-tubulin proteins in bovine microtubule preparations were found to remain soluble when tubulin was removed prior to heating. Addition of purified tubulin or bovine serum albumin to the preparation restored the selective heat stability normally seen in microtubule protein preparations.