Figure 1. Crystal structure of p27/CDK2/CyclinA complex (PDB ID: 1JSU¹¹).

Color scheme is, CDK2 blue, Cyclin A red, and p27 green. Important regions of p27 are labeled and the location of Tyr88 in 3₁₀ helix of p27 is shown in sphere representation. The position of β2 strand of CDK2, which forms hybrid β-sheet with p27 β-strand is shown and labeled. Notably, the β1 strand and G-loop of CDK2 were missing in this structure. For comparison, the position of β2 strand and that of the G-loop and β1 strand in active CDK2 is shown (in grey, also labelled in grey) from the crystal structure of CDK2/CyclinA complex (PDB ID: 1QMZ²⁸) by superposing the two crystal structures.