Binds and inhibits CYCD2-1/CDKA-1 complex kinase activity. May target specifically CDKA-1. Specifically interacts with CDKA-1, but not with CDKB1-1. Interacts with CYCD4-1. Binds to FBL17. Homogeneously distributed. Accumulates strongly in vegetative cell nuclei immediately after asymmetric division and disappears later. Expressed in flowers, in developing pollen, and at lower levels in roots and leaves. Present in uninucleate microspore and bicellular pollen. Ubiquitinated by SCF(FBL17). Ubiquitination leads to its subsequent degradation, thus controlling cell cycle progression. Belongs to the CDI family. ICK/KRP subfamily.