The present invention relates to isolated nucleic acid sequences that encode human olfactory cyclic nucleotide gated (CNG) channel subunits, and the corresponding polypeptides. The invention further relates to the use of human CNG channels to profile, screen for, and identify compounds that modulate the human olfactory CNG channel. More specifically, the invention relates to the expression of the human olfactory CNG channel in cells, preferably mammalian cells, and the use of these cells in high throughput cell-based assays to identify compounds that enhance or block human olfactory CNG function. Compounds that activate the olfactory CNG channel will enhance smell and can be used to make foods more palatable for individuals with attenuated olfactory function. Conversely, compounds that inhibit the olfactory CNG channel will inhibit smell and can be use to block malodors. Additionally, the invention relates to the use of cell-based olfactory CNG channel assays to identify modulates of G-protein coupled receptor (GPCRs) and other proteins that regulate cyclic nucleotide levels.