Mammalian tubulins and actins attain their native con-formation following interactions with CCT (the cytosolic chaperonin containing t-complex polypeptide 1). To study the b-tubulin folding in lower eukaryotes, an isotype of b-tubulin (b-T1) from the Antarctic ciliate Euplotes focardii, was expressed in Escherichia coli. Folding analysis was performed by incubation of the 35 S-labeled, denatured b-T1 in the presence, or absence, of purified rabbit CCT and cofactor A, a polypeptide that stabilizes folded monomericb-tubulin. .
