THE ARABIDOPSIS CKS1AT PROTEIN BINDS THE CYCLIN-DEPENDENT KINASES CDC2AAT AND CDC2BAT

In Arabidopsis, two cyclin-dependent kinases (CDK), Cdc2aAt and Cdc2bA t. have been described, Here, we hale used the yeast two-hybrid system to identify Arabidopsis proteins interacting with Cdc2aAt, Three diff erent clones were isolated, one of which encodes a Suc1/Cks1 homologue , The functionality of the Arabidopsis Suc1/Cks1 homologue, designed C ks1At, was demonstrated by its ability to rescue the temperature-sensi tive cde2-L7 strain of fission yeast at low and intermediate expressio n levels, In contrast, high cks1At expression levels inhibited cell di vision in both mutant and wild-type ? east strains, Cks1At binds both Cdc2aAt and Cdc2bAt in vivo and in vitro, Furthermore, we demonstrate that the fission yeast Suc1 binds Cdc2aAt but only weakly Cdc2bAt, whe reas the human CksHs1 associated exclusively with Cdc2aAt. (C) 1997 Fe deration of European Biochemical Societies.