... c-tubulin binds GTP in a plus-end cleftenclosed by residues G 11, Q12,C13, Q16, G1 01, N102, S140, A142, G143, G144, T145, V1 71, P173,N207, F225, I228, and N229 (where the residuesshown underlined ... cluster of substitutions in H 11 and the H 11- H12 loop of the two c-tubulins cause polaritychanges at the plus end (Fig. 4) that would differentiate the longitudinal interactions formed by c-T1 and ... structures of the a- and b-tubulin [29– 31] and of the proteins that form the ribo-somal stalk [32]. In the present study, we characterized the two c-tubulin isotypes, c-T1 and c-T2, of E. focardii...