PER-TIM interactions in living Drosophila cells: an interval timer for the circadian clock.
In contrast to current models, fluorescence resonance energy transfer measurements using a single-cell imaging assay with fluorescent forms of PER and TIM showed that these proteins bind rapidly and persist in the cytoplasm while gradually accumulating in discrete foci. After approximately 6 hours, complexes abruptly dissociated, as PER and TIM independently moved to the nucleus in a narrow time frame. The per(L) mutation delayed nuclear accumulation in vivo and in our cultured cell system, but without affecting rates of PER/TIM assembly or dissociation. This finding points to a previously unrecognized form of temporal regulation that underlies the periodicity of the circadian clock.
Meyer
Pablo
P
Laboratory of Genetics, Rockefeller University, 1230 York Avenue, New York, NY 10021, USA.
Saez
Lino
L
Young
Michael W
MW
D021581:Active Transport, Cell Nucleus; D000818:Animals; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D002940:Circadian Rhythm / Q000502:physiology*; D003593:Cytoplasm / Q000378:metabolism; D029721:Drosophila Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster; D031541:Fluorescence Resonance Energy Transfer; D008954:Models, Biological; D009687:Nuclear Proteins / Q000378:metabolism*; D056950:Period Circadian Proteins; D011485:Protein Binding; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013997:Time Factors
D029721:Drosophila Proteins; D009687:Nuclear Proteins; C539040:PER protein, Drosophila; D056950:Period Circadian Proteins; D011993:Recombinant Fusion Proteins; C096445:tim protein, Drosophila