This gene encodes a member of the basic-helix-loop-helix-Per-Arnt-Sim (bHLH-PAS) superfamily of transcription factors. The encoded protein acts as a partner for several sensor proteins of the bHLH-PAS family, forming heterodimers with the sensor proteins that bind regulatory DNA sequences in genes responsive to developmental and environmental stimuli. Under hypoxic conditions, the encoded protein complexes with hypoxia-inducible factor 1alpha in the nucleus and this complex binds to hypoxia-responsive elements in enhancers and promoters of oxygen-responsive genes. A highly similar protein in mouse forms functional complexes with both aryl hydrocarbon receptors and Single-minded proteins, suggesting addition roles for the encoded protein in the metabolism of xenobiotic compounds and the regulation of neurogenesis, respectively. Protein Interaction Partner: TRIM42, CEP57L1, RFX6, MIPOL1, DYDC1, SSX2IP, DTX2, SYCE1, RIMBP3, ZNF341, LZTS2, USHBP1, CEP63, CCDC33, NPAS3, RINT1, NDE1, ADAMTSL4, MTUS2, IKZF3, RBCK1, SPAG5, TACC3, CALCOCO2, SORBS3, PDE4DIP, TRAF4, BZRAP1, TFIP11, SSBP3, DGCR6, NCOA3, TRIP6, TRAF2, Protein Size: 217