Formation of Cyclin A:Cdc2 complexes

Cyclin A is synthesized and associates with Cdc2 in G1. Cyclin dependent kinases are themselves catalytically inactive due to the fact that their active sites are blocked by a portion of the CDK molecule itself. Binding to their corresponding cyclin partner results in a conformational change that partially exposes the active site.

Cyclin A在G1期被合成并与Cdc2结合。由于其活性位点被CDK分子自身的一部分所阻隔，依赖周期蛋白的激酶本身在催化上处于不活跃状态。与相应的周期蛋白伙伴的结合导致构象变化，部分暴露了活性位点。