Fig. 6. Dynamic ordering of the hydrophobic core.

(A) Most of the elements of the hydrophobic core (teal and gray) are stable in both active and inactive conformational states. This includes β1 through β8 and the catalytic loop. These elements, as well as the C-spine, are anchored to the F helix by hydrophobic interactions. The assembly of the R-spine completes the hydrophobic core and positions the Mg loop and β9 (red). (B) This active conformation, particularly the β8-β9 sheet, is further stabilized by phosphorylation at Thr¹⁹⁷ in the activation loop.