CDT1 is a component of the replication licensing system and promotes the loading of the mini-chromosome maintenance complex onto chromatin. Geminin is an inhibitor of CDT1 and prevents inappropriate re-initiation of replication on an already fired origin. This region of CDT1 binds to Geminin [1].

1: Structural basis for inhibition of the replication licensing factor Cdt1 by geminin. Lee C, Hong B, Choi JM, Kim Y, Watanabe S, Ishimi Y, Enomoto T, Tada S, Kim Y, Cho Y; Nature. 2004;430:913-917. PMID:15286659