The α- and β-tubulin folding pathways

The α—β tubulin heterodimer is the subunit from which microtubules are assembled. The pathway leading to correctly folded α- and β-tubulins is unusually complex: it involves cycles of ATP-dependent interaction of newly synthesized tubulin subunits with cytosolic chaperonin, resulting in the production of quasi-native folding intermediates, which must then be acted upon by additional protein cofactors. These cofactors form a supercomplex containing both α- and β-tubulin polypeptides, from which native heterodimer is released in a GTP-dependent reaction. Here, we discuss the current state of our understanding of the function of cytosolic chaperonin and cofactors in tubulin folding.