Structural basis for activation of the autoinhibitory C-terminal kinase domain of p90 RSK2

The X-ray structure at 2.0-Å resolution of the p90 ribosomal S6 kinase 2 C-terminal kinase domain revealed a C-terminal autoinhibitory αL-helix that was embedded in the kinase scaffold and determines the inactive kinase conformation. We suggest a mechanism of activation through displacement of the αL-helix and rearrangement of the conserved residue Glu500, as well as the reorganization of the T-loop into the active conformation.