Neuronal PAS domain protein 2 (NPAS2)

NPAS2 is a **transcription factor of the bHLH-PAS family** that regulates circadian rhythms, sleep–wake cycles, and diverse physiological processes in mammals. It forms heterodimers with BMAL1, binding E-box DNA sequences in core clock gene promoters to control their expression through well-characterized feedback loops[1][2][3][4][5][6][7]. NPAS2 is distinguished from its paralogue CLOCK by unique expression patterns and regulatory features, including gas (carbon monoxide)- and heme-based sensing, which directly influences its DNA binding and transcriptional activity. NPAS2’s functions extend from central nervous system regulation to metabolic control in the liver, modulation of neurotransmitter systems, and response to cellular stress and DNA damage. Dysregulation or genetic variation of NPAS2 is associated with disease, especially cancer, sleep and mood disorders, and cardiovascular conditions. NPAS2 is under investigation as both a therapeutic target and a biomarker for certain disease states owing to its central role in circadian biology.

Other names

Member of PAS protein 4MOP4PASD4bHLHe9basic helix–loop–helix-PAS protein MOP4class E basic helix–loop–helix protein 9PAS domain-containing protein 4neuronal PAS2

Drugs or compounds acting on NPAS2 would generally modulate circadian clock function, metabolic regulation, or related transcriptional programs; the mechanism could involve impacting NPAS2-BMAL1 heterodimer activity, heme-binding regulation, and gas (CO)-responsive transcriptional activity[2][4].