to determine if mixtures of tubulin isotypes segregate into different classes of polymers in vitro , we used immunoelectron microscopy to examine the composition of microtubule copolymers that assembled from mixtures of purified tubulin subunits from chicken brain and erythrocytes , each of which has been shown to exhibit distinct assembly properties in vitro .
C0026046
microtubule
C0041348
tubulin