COMMON THREADS IN EUKARYOTIC CIRCADIAN SYSTEMS

Within the past 18 months, common regulatory patterns have emerged amo ng eukaryotic circadian systems - extending from fungi through to mamm als. Heterodimeric complexes of PAS-domain-containing transcription fa ctors play positive roles in clack-associated feedback loops, and clas sic clock proteins like FREQUENCY (FRQ), PERIOD (PER), and TIMELESS (T IM) appear as negative elements. Post-transcriptional control governs the amount and type of FRQ and makes the clock responsive to temperatu re.