Protein sequence alignment of deduced amino-acid sequences of 347 human olfactory receptors. The alignment is color-coded according to the physicochemical properties and degree of conservation of amino-acid residues. The following side-chain-based coloring convention for groups of amino acids was used: Ile, Leu, Met, Val, Phe, Tyr, Ala, Trp (green), Lys, Arg (blue), His (light blue), Asp, Glu (red), Ser, Thr (orange), Pro (purple), Gly (magenta), Cys (yellow), Gln, Asn (grey). Positions with greater than 50% conservation (based on the amino-acid similarity groups shown above and PAM250 matrix) are shown as inverse characters on solid background. At the bottom of the figure, locations of the predicted membrane-spanning domains (TM1-7), intracellular loops (IC1-3) and extracellular loops (EC1-3) are indicated by horizontal bars. Positions of the three pairs of conserved cysteine residues are shown as asterisks. This figure is available as an additional data file in PDF format.