Nuclear receptor subfamily 1 group D member 1 (NR1D1)

Transcriptional repressor which coordinates circadian rhythm and metabolic pathways in a heme-dependent manner. Integral component of the complex transcription machinery that modulates circadian rhythmicity and forms a critical negative limb of the circadian clock by directly repressing the expression of core clock parts ARTNL/BMAL1, CLOCK and CRY1.

Also regulates genes involved in metabolic functions, including lipid and bile acid metabolism, adipogenesis, gluconeogenesis and the macrophage inflammatory response. Acts as a receptor for heme which stimulates its interaction with the NCOR1/HDAC3 corepressor complex, enhancing transcriptional repression.