the order: Tas1r2 – Tas1r1 – Tas1r3. Their human orthologues reside in a region of conserved synteny in the short arm of human chromosome 1 (1p36) in the same order: TAS1R2 – TAS1R1 – TAS1R3. The mouse Tas1r genes contain six coding exons that are translated into 842–858 amino acid proteins. The T1R proteins have a predicted secondary structure that includes seven transmembrane helices forming a heptahelical domain, and a large extracellular N-terminus composed of a venus flytrap (VFT) domain and a cysteine-rich domain connected to the heptahelical domain.
