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. Author manuscript; available in PMC: 2009 Apr 4.
Published in final edited form as: J Mol Biol. 2008 Jan 31;377(4):1279–1295. doi: 10.1016/j.jmb.2008.01.059

Figure 1.

Figure 1

Schematic sketch of the catalytic cycle of GroEL. SP is captured by GroEL in the T state. Binding of ATP triggers the equilibrium T ↔ R transition. Subsequently, GroES binding encapsulates the SP (assuming it can fit into the expanded cavity) leading to the R → R′ transition. Hydrolysis of ATP results in the R′ → R″ transition. The volume of the cavity doubles from 85, 000Å3 in the T state to about 170, 000 Å3 in the R″ (and presumably in R′) state. Folding of SP in the largely hydrophilic cavity in R′ or R″ state can occur with some probability. Interring communication, shown by solid blue arrow, signals release of SP, ADP, and phosphate. Kinetic partitioning of SP, which is shown to occur for clarity in the bulk, could occur in the cell. In other words, folding to the native state or transition to the ensemble of misfolded structures can take place upon SP encapsulation.