Nuclear localization of protein kinase U-alpha is regulated by 14-3-3.
14-3-3 proteins are intracellular, dimeric molecules that bind to and modify the activity of several signaling proteins. We used human 14-3-3zeta as a bait in the yeast two-hybrid system to screen a murine embryonic cDNA library. One interacting clone was found to encode the carboxyl terminus of a putative protein kinase. The coding sequence of the human form (protein kinase Ualpha, PKUalpha) of this protein kinase was found in GenBank(TM) on the basis of sequence homology. The two-hybrid clone was also highly homologous to TOUSLED, an Arabidopsis thaliana protein kinase that is required for normal flower and leaf development. PKUalpha has been found by coimmunoprecipitation to bind to 14-3-3zeta in vivo. Our confocal laser immunofluorescence microscopic experiments revealed that PKUalpha colocalizes with the cytoplasmic intermediate filament system of cultured fibroblasts in the G(1) phase of the cell cycle. PKUalpha is found in the perinuclear area of S phase cells and in the nucleus of late G(2) cells. Transfection of cells with a dominant negative form of 14-3-3eta promotes the nuclear localization of PKUalpha. These results suggest that the subcellular localization of PKUalpha is regulated, at least in part, by its association with 14-3-3.
Zhang
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Center for Cardiovascular Research, Departments of Medicine, Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Xing
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Muslin
A J
AJ
D048948:14-3-3 Proteins; D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D029681:Arabidopsis Proteins; D002453:Cell Cycle; D003001:Cloning, Molecular; D019926:Cyclin B / Q000378:metabolism; D056744:Cyclin B1; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics*; D011485:Protein Binding; D011494:Protein Kinases / Q000737:chemistry / Q000235:genetics*; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000235:genetics*; D011506:Proteins / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D016415:Sequence Alignment; D014162:Transfection; D014446:Tyrosine 3-Monooxygenase; D015003:Yeasts
D048948:14-3-3 Proteins; D029681:Arabidopsis Proteins; C534699:CCNB1 protein, human; C534700:Ccnb1 protein, mouse; D019926:Cyclin B; D056744:Cyclin B1; D009687:Nuclear Proteins; D011506:Proteins; D012333:RNA, Messenger; C482984:YWHAH protein, human; D014446:Tyrosine 3-Monooxygenase; D011494:Protein Kinases; C084661:tousled protein, Arabidopsis; C121377:protein kinase U; D017346:Protein Serine-Threonine Kinases