brief chymotryptic digestion and subsequent centrifugation of microtubules preformed with pure tubulin and map2 permitted separation of microtubule-bound map2 fragments ( molecular mass = approximately 215 , approximately 180 , and approximately 36 kda ) from unbound fragments ( molecular mass = approximately 240 , approximately 180 , and approximately 140 kda ) .
C0026046
microtubules
C0041348
tubulin