InterPro domain: IPR044275

This entry represents a group of plant cyclin-dependent kinase inhibitors (CKIs), including KRP1-7 (Kip-related proteins 1-7) from Arabidopsis [ 1 ].

Plant CKIs fall into 2 distinct families, KIP-RELATED PROTEINS (KRPs) and SIAMESE-RELATED proteins (SMRs). KRPs share very little sequence similarity with mammalian KIP proteins outside the C-terminal conserved region. Compare to mammalian CKIs, plant KRP1-KRP7 bind to active cyclin D2 (CYCD2)/CDKA and CYCD2/CDKB complexes to a similar extent, however, they inhibit kinase activity to a different extent [ 2 ]. KRPs function as a dose-dependent cell cycle inhibitors and have an important function in cell proliferation as well as in cell cycle exit and in turning from a mitotic to an endoreplicating cell cycle mode [ 3 ].

1. A plant cyclin-dependent kinase inhibitor gene. Nature 386, 451-2
2. Arabidopsis KRPs have distinct inhibitory activity toward cyclin D2-associated kinases, including plant-specific B-type cyclin-dependent kinase. FEBS Lett 580, 336-40
3. Novel functions of plant cyclin-dependent kinase inhibitors, ICK1/KRP1, can act non-cell-autonomously and inhibit entry into mitosis. Plant Cell 17, 1704-22