Nucleus {By
Similarity}. Cytoplasm, perinuclear region {By
Similarity}. Note=Nuclear at specific periods of the day. First accumulates in the perinuclear region about one hour before translocation into the nucleus. Interaction with Tim is required for nuclear localization (By similarity). {By
Similarity}.
Essential for biological clock functions. Determines the period length of circadian and ultradian rhythms; an increase in PER dosage leads to shortened circadian rhythms and a decrease leads to lengthened circadian rhythms. Essential for the circadian rhythmicity of locomotor activity, eclosion behavior, and for the rhythmic component of the male courtship song that originates in the thoracic nervous system. The biological cycle depends on the rhythmic formation and nuclear localization of the TIM-PER complex. Light induces the degradation of TIM, which promotes elimination of PER. Nuclear activity of the heterodimer coordinatively regulates PER and TIM transcription through a negative feedback loop. Behaves as a negative element in circadian transcriptional loop. Does not appear to bind DNA, suggesting indirect transcriptional inhibition (By similarity). {By
Similarity}.
National and Kapodistrian University of Athens
Department of Biology
Biophysics & Bioinformatics Laboratory