| The Per-Arnt-Sim (PAS) domain was identified as a 270 amino acid motif that mediates associations among various PAS family transcription factors. PAS domain family members include period proteins (Per1, Per2 and Per3), Arnt 1 (also designated HIF-1beta), Arnt 2, Ah Receptor, BMAL1 (for Brain and Muscle Arnt-like protein 1, also designated Arnt 3, TIC, JAP3 or MOP3), Clock, single-minded proteins (SIM1 and SIM2) and hypoxia-inducible factors such as HIF-1(alpha) (also designated MOP1), EPAS-1 (also designated HIF-2(alpha), MOP2 or HLF) and HIF-3(alpha). The PAS family also contains a neuronal specific transcription factor known as NPAS2 that is involved the development and maintenance of learning and memory pathways. NPAS2, which is also designated PAS 4/MOP4, associates with MOP3 to activate transcription. The protein encoded by this gene is a basic helix-loop-helix protein that forms a heterodimer with CLOCK. This complex binds an E-box upstream of the PER1 gene, activating this gene and possibly other circadian rhythym-associated genes. |
