title: Differential phosphorylation activities of CDK-activating kinases in Arabidopsis thaliana.
abstract: Activation of cyclin-dependent kinases (CDKs) requires phosphorylation of a threonine residue within the T-loop by a CDK-activating kinase (CAK). Here we isolated an Arabidopsis cDNA (CAK4At) whose predicted product shows a high similarity to vertebrate CDK7/p40(MO15). Northern blot analysis showed that expressions of the four Arabidopsis CAKs (CAK1At-CAK4At) were not dependent on cell division. CAK2At- and CAK4At-immunoprecipitates of Arabidopsis crude extract phosphorylated CDK and the carboxy-terminal domain (CTD) of the largest subunit of RNA polymerase II with different preferences. These results suggest the existence of differential mechanisms in Arabidopsis that control CDK and CTD phosphorylation by multiple CAKs.
authors.affiliation: Institute of Molecular and Cellular Biosciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-0032, Japan.
authors.forename: Akie
authors.initials: A
authors.lastname: Shimotohno
authors.forename: Satoko
authors.initials: S
authors.lastname: Matsubayashi
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Yamaguchi
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Uchimiya
authors.forename: Masaaki
authors.initials: M
authors.lastname: Umeda
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D018844:Cyclin-Dependent Kinases / Q000235:genetics / Q000378:metabolism*; D005816:Genetic Complementation Test; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D012319:RNA Polymerase II / Q000378:metabolism; D015003:Yeasts / Q000235:genetics; D000095043:Cyclin-Dependent Kinase-Activating Kinase
chemical_list: D029681:Arabidopsis Proteins; D011494:Protein Kinases; C471231:CAK2 protein, Arabidopsis; C471232:CAK3 protein, Arabidopsis; C471233:CAK4 protein, Arabidopsis; D018844:Cyclin-Dependent Kinases; D012319:RNA Polymerase II; D000095043:Cyclin-Dependent Kinase-Activating Kinase