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. 2018 Oct 12;62(6):737–751. doi: 10.1042/EBC20180031

Figure 5. Proposed models of the structural basis of dynamic instability.

Figure 5

Recent cryo-EM studies highlight two potential structural sources of dynamic instability: (i) lateral loosening at the MT seam (white arrow) in the GDP state, but not in the GTP-like (GMPCPP) state or the GTPγS state [26] that shares some characteristics with the GDP.Pi state [23] and (ii) two-step lateral loosening between all PFs in the MT lattice, first on transition to GDP.Pi state and then to GDP state [23]. Both scenarios are depicted at the top part of the figure using schematics of MT cross-sections in transversal plane. Due to PF stagger, the cross-section perpendicular to MT axis runs across both α- (lighter) and β-tubulin (darker), enabling depiction of sequential lateral loosening between the subunits (curved arrows). These observations can be summarized in a single coherent model of MT catastrophe shown in the bottom part of the figure, as the studies agree that the seam appears to be the weakest link of the lattice.