Abstract
The PAS domain is a versatile protein fold that is found in many archaeal, bacterial, and plant proteins. It acts as a ligand-binding environmental sensor for detecting environmental changes in light intensity, oxygen concentration, and redox potentials. In mammals, several PAS domain-containing factors function as sensor molecules, including HIF, NPAS2, and AhR. In the mammalian circadian system, seven Clock gene products are PAS factors: PER1, PER2, PER3, CLOCK, NPAS2, BMAL1, and BMAL2. These clock genes are involved in the generation of circadian oscillations, the entrainment of animals to 24-hour light-dark cycles, and the output of signals from the central clock to the periphery. To investigate the system regulating the circadian clock with input from the environment, we established a system to monitor clock oscillations using a Bmal1 promoter construct as a reporter. Utilization of this system should facilitate the identification of factors that affect the circadian phase or amplitude. [Jpn J Physiol 54 Suppl:S39 (2004)]
