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. Author manuscript; available in PMC: 2021 May 15.
Published in final edited form as: Science. 2021 Feb 12;371(6530):eabd0951. doi: 10.1126/science.abd0951

Figure 1. Extracellular signals and the molecular clock.

Figure 1.

Simplified scheme of the molecular clock/oscillator. Right – the core transcriptional activators circadian locomotor output cycles protein kaput (CLOCK) and brain and muscle ARNT-like 1 (BMAL1), together with the repressors period (PER) and cryptochrome (CRY) and interlocked auxiliary loops (regulating D-boxes and ROR elements), control a near 24-hr cycle of each other’s expression as well as clock controlled output genes (CCGs). Left – extracellular signals that engage the clock through various means to set period, phase, amplitude and output. PTM – posttranslational modification; cAMP – cyclic adenosine monophosphate; PAS – Per-Arnt-Sim; ROR –RAR-related orphan receptor; REV-ERB – nuclear receptor subfamily 1 group D; DBP – albumin D-box binding protein; Tef – thyrotroph embryonic factor; Hlf – hepatic leukemia factor; NFIL3 – nuclear factor, interleukin 3 regulated.