Table 1 Circadian clock genes and their functions in Drosophila and mice
Organism | Gene | Protein function | Clock function |
|---|---|---|---|
Drosophila | per | Binds to dClk-Cyc as a heterodimer with Tim | Inhibits dClk-Cyc-dependent transcription |
| Â | tim | Stabilizes phosphorylated Per | Contributes to delayed Per accumulation |
| Â | Â | Promotes Per nuclear localization | Acts with Per to inhibit dClk-Cyc-dependent transcription |
| Â | Â | Binds to dClk-Cyc as a heterodimer with Per | Mediates phase-resetting in response to light |
| Â | Â | Degraded in response to light | Â |
| Â | dClk | Forms a heterodimeric complex with Cyc | Activates per and tim transcription and inhibits dClk transcription |
| Â | Cyc (Bmal1) | Forms a heterodimeric complex with dClk | Activates per and tim transcription and inhibits dClk transcription |
|  | dbt (CK1ε) | Phosphorylates Per | Destabilizes Per |
| Â | cry | Photoreceptor element that binds to Tim | Initiates light signaling required for phase resetting |
Mouse | mPer1 | Interacts with Clock-Bmal1? | Moderate inhibition of Clock-Bmal1-dependent transcription |
| Â | mPer2 | Interacts with Clock-Bmal1? | Activation of Bmal1 transcription |
| Â | Â | Â | Moderate inhibition of Clock-Bmal1-dependent transcription |
| Â | mPer3 | Interacts with Clock-Bmal1? | Moderate inhibition of Clock-Bmal1-dependent transcription |
| Â | mTim | Interacts with Clock-Bmal1? | Moderate inhibition of Clock-Bmal1-dependent transcription |
| Â | Clock | Forms a heterodimeric complex with Bmal1 | Activates mPer1-3 and mCry1 |
| Â | Bmal1 | Forms a heterodimeric complex with Clock | Activates mPer1-3 and mCry1 |
|  | CK1ε (tau) | Phosphorylates mPer1 and mPer2 | Destabilizes mPers |
| Â | mCry1 | Dimerizes with mPer1-3 | Strongly inhibits Clock-Bmal1-dependent transcription |
| Â | Â | Binds to Clock-Bmal1 | Â |
| Â | Â | Promotes mPer1-3 nuclear localization | Â |
| Â | mCry2 | Dimerizes with mPer1-3 | Strongly inhibits Clock-Bmal1-dependent transcription |
| Â | Â | Binds to Clock-Bmal1 | Â |
| Â | Â | Promotes mPer1-3 nuclear localization | Â |