CyclinA-cyclin-dependent kinase2 (CDK2)-ATP complex

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Cyclin-dependent kinase (CDK - blue)-cyclin (green) complexes require phosphorylation on the CDK subunit for full activation of their Ser/Thr protein kinase activity. The crystal structure of the phosphorylated CDK2-CyclinA-ATP gamma S complex has been determined at 2.6 A resolution. The phosphate group, which is on the regulatory T-loop of CDK2, is mostly buried (spacefill grey), its charge being neutralized by three Arg side chains. The arginines help extend the influence of the phosphate group through a network of hydrogen bonds to both CDK2 and cyclinA. Comparison with the unphosphorylated CDK2-CyclinA complex shows that the T-loop moves by as much as 7 A, and this affects the putative substrate binding site as well as resulting in additional CDK2-CyclinA contacts. The phosphate group thus acts as a major organizing centre in the CDK2-CyclinA complex.


[1] Russo AA; Jeffrey PD; Pavletich NP (1996) Nat Struct Biol 3: 696-700.

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