Remembrance of things PAS: regulation of development by bHLH-PAS proteins

bHLH-PAS proteins are regulators of developmental and physiological events that are well conserved between vertebrates and invertebrates. Recent studi es using mouse knockouts of bHLH-PAS genes have provided novel insight into the roles of hypoxia inducible factors in controlling oxygen-regulated dev elopment and homeostasis, and the role of Singleminded-1 in regulating deve lopment and transcription in the hypothalamus. The Drosophila spineless and vertebrate Aryl hydrocarbon receptor bHLH-PAS orthologs both function in c hemosensory processes, but in fundamentally different ways. Spineless contr ols antennal, limb, and sensory cell development, whereas the Aryl hydrocar bon receptor regulates the response to toxin metabolism. Structural analyse s of the PAS domain provide insight into how this interaction domain can ac t as ligand-binding environmental sensor and signal transducer.