Figure 4. Folding trajectory of tubulin.

(A) Model showing the position of tubulin within the open (left) and closed (right) conformations of CCT. In the open form, tubulin is in an amorphous state interacting with the N- and C-termini of the CCT subunits (black lines). In the closed form, the tubulin is released from between the CCT rings as the termini redistribute. The tubulin moves into the CCT folding chamber and interacts with positively charged patches in the apical domains along the inner walls of the chamber. (B) Model representing the four observed states of tubulin folding inside the folding cavity of closed CCT (PDB 7NVN). The domains of tubulin are indicated: N = the N terminal domain, C = the C terminal domain, Core = the helical core domain, Mid = the middle domain. Lines represent unstructured regions in each folding state. See text for details.