description
Within the compact cilia of the olfactory receptor neurons (ORNs) a cascade of enzymatic activity transduces the binding of an odorant molecule to a receptor into an electrical signal that can be transmitted to the brain. Odorant molecules bind to a receptor protein (R) coupled to an olfactory specific Gs-protein (G) and activate a type III adenylyl cyclase (AC), increasing intracellular cAMP levels. cAMP targets an olfactory-specific cyclic-nucleotide gated ion channel (CNG), allowing cations, particularly Na and Ca, to flow down their electrochemical gradients into the cell, depolarizing the ORN. Furthermore, the Ca entering the cell is able to activate a Ca-activated Cl channel, which would allow Cl to flow out of the cell, thus further increasing the depolarization. Elevated intracellular Ca causes adaptation by at least two different molecular steps: inhibition of the activity of adenylyl cyclase via CAMKII-dependent phosphorylation and down-regulation of the affinity of the CNG channel to cAMP

external resources
NCBI:83087
KEGG:hsa04740
PUBMED:19652915
PUBMED:22735517
PUBMED:11557990
PUBMED:19306880
PUBMED:16269360
PUBMED:19941039
PUBMED:20145624
PUBMED:12488531
PUBMED:22875451
PUBMED:24733839
PUBMED:10944513

genes
ADCY3 , GRK2 , GRK3 , ARRB1 , ARRB2 , CALM1 , CALM2 , CALM3 , CALML3 , CAMK2A , CAMK2B , CAMK2D , CAMK2G , CNGB1 , CNGA2 , CNGA3 , CNGA4 , GNAL , GNB1 , GNG7 , GUCY2D , OR1D2 , OR1F1 , OR2C1 , OR3A1 , OR3A2 , PDE1A , PDE1C , PDE2A , PDE1B , PRKACA , PRKACB , PRKACG , PRKG1 , PRKG2 , RGS2 , SLC8A2 , SLC8A1 , SLC8A3 , OR2H2 , OR1A1 , OR1D5 , OR1E1 , OR1E2 , OR1G1 , OR3A3 , OR6A2 , OR5I1 , OR52A1 , OR1C1 , OR1A2 , OR2F1 , OR2B6 , OR1J4 , OR2M4 , OR2L2 , OR2K2 , OR7A17 , OR5L2 , OR5K1 , OR5H1 , OR10J1 , OR8G2P , OR8B8 , OR8G1 , OR10A3 , OR12D2 , OR11A1 , OR10H3 , OR10G3 , OR10G2 , OR10H2 , OR10H1 , OR8B2 , OR7E24 , OR7C2 , OR7A5 , OR7C1 , OR4F4 , OR4F3 , OR4E2 , OR4E1 , OR4D1 , OR2W1 , OR2V1 , OR2T1 , OR2J2 , OR2H1 , OR1L3 , OR1L1 , OR1J2 , GNG13 , CALML5 , OR2S2 , ANO2 , OR13A1 , OR5H6 , OR5H2 , OR4K5 , OR51G1 , OR51B4 , OR51B2 , OR52N1 , OR4F5 , OR2A4 , OR4K1 , OR5AC2 , OR11H1 , OR4F17 , OR4K15 , OR8J3 , OR51G2 , OR51E2 , OR4P4 , OR4C15 , OR4A5 , OR4A16 , OR4A15 , OR10W1 , OR2AE1 , OR4F16 , OR6N2 , OR6K2 , OR2L5 , OR2G3 , OR2G2 , OR2C3 , OR5V1 , OR2B2 , OR12D3 , NCALD , CALML4 , OR52E2 , OR52J3 , OR51L1 , OR51A7 , OR51S1 , OR51F2 , OR52R1 , OR4C46 , OR4X2 , OR4B1 , OR52M1 , OR52K2 , OR5P2 , OR5P3 , OR8I2 , OR2D3 , OR2D2 , OR52W1 , OR56A4 , OR56A1 , OR2AP1 , OR10P1 , OR10AD1 , OR10A7 , OR4K14 , OR4L1 , OR11H6 , SLC24A4 , OR4D2 , OR7D4 , OR7G1 , OR1M1 , OR1I1 , OR10H4 , OR2M5 , OR2M3 , OR2T12 , OR14C36 , OR2T34 , OR2T10 , OR2T4 , OR2T11 , OR10J5 , OR2B11 , OR10T2 , OR6P1 , OR10X1 , OR10Z1 , OR6K6 , OR6N1 , OR9A4 , OR2Y1 , OR9A2 , OR2A14 , OR6B1 , OR2F2 , OR13C5 , OR13C8 , OR13C3 , OR13C4 , OR13F1 , OR1L8 , OR1N2 , OR1N1 , OR52B4 , OR52I2 , OR51E1 , OR10A5 , OR2AG1 , OR6B3 , OR1Q1 , OR7D2 , CALML6 , OR56B4 , OR8U1 , OR4C16 , OR4C11 , OR4S2 , OR4C6 , OR5D14 , OR5L1 , OR5D18 , OR5AS1 , OR8K5 , OR5T2 , OR8H1 , OR8K3 , OR8J1 , OR5R1 , OR5M3 , OR5M8 , OR5M11 , OR5AR1 , OR8B12 , OR8G5 , OR10G8 , OR10G9 , OR10S1 , OR6T1 , OR4D5 , OR6Q1 , OR9I1 , OR9Q1 , OR9Q2 , OR1S2 , OR1S1 , OR10Q1 , OR5B17 , OR5B21 , OR5A2 , OR5A1 , OR4D6 , OR4D11 , OR6C74 , OR6C3 , OR2T6 , OR1L4 , OR52B2 , OR4C3 , OR4S1 , OR51F1 , OR51B5 , OR10AG1 , OR5J2 , OR4C13 , OR4C12 , OR51V1 , OR8D1 , OR8D2 , OR8B4 , OR9G4 , OR10A4 , OR6C6 , OR4N4 , OR2Z1 , OR10H5 , OR2L13 , OR14A16 , OR2V2 , OR13C9 , OR13D1 , OR8D4 , OR5F1 , OR5AP2 , OR52L1 , OR2AG2 , OR52B6 , OR2AT4 , OR10A2 , OR6C2 , OR6C4 , OR8S1 , OR6S1 , OR6F1 , OR2W3 , OR2T8 , OR2T3 , OR10R2 , OR2T29 , OR6V1 , OR2A12 , OR2A1 , OR1J1 , OR1B1 , OR13H1 , OR56B1 , OR6B2 , OR52K1 , OR52I1 , OR51D1 , OR52A5 , OR51B6 , OR51M1 , OR51Q1 , OR51I1 , OR51I2 , OR52D1 , OR52H1 , OR52N4 , OR52N5 , OR52N2 , OR52E6 , OR52E8 , OR52E4 , OR56A3 , OR56A5 , OR10A6 , OR4X1 , OR5D13 , OR5D16 , OR5W2 , OR8H2 , OR8H3 , OR5T3 , OR5T1 , OR8K1 , OR5M9 , OR5M10 , OR5M1 , OR9G1 , OR5AK2 , OR5B2 , OR5B12 , OR5AN1 , OR4D10 , OR4D9 , OR10V1 , OR6X1 , OR6M1 , OR10G4 , OR10G7 , OR8B3 , OR8A1 , OR6C1 , OR6C75 , OR6C76 , OR6C70 , OR4N2 , OR4K2 , OR4K13 , OR4K17 , OR4N5 , OR11G2 , OR11H4 , OR5AU1 , OR4M2 , OR4F6 , OR4F15 , OR7G2 , OR7G3 , OR7A10 , OR10K2 , OR10K1 , OR6Y1 , OR6K3 , OR11L1 , OR2L8 , OR2AK2 , OR2L3 , OR2M2 , OR2T33 , OR2M7 , OR2G6 , OR2A25 , OR13J1 , OR13C2 , OR1L6 , OR5C1 , OR1K1 , OR2A5 , OR2A7 , OR51T1 , OR51A4 , OR51A2 , OR2T2 , OR2T5 , OR14I1 , OR5K2 , OR2A42 , OR2T27 , OR4A47 , OR5H14 , OR5H15 , OR5K3 , OR5K4 , OR6C65 , OR6C68 , OR11H12 , OR4F21 , OR5B3 , OR9K2 , OR4Q3 , OR4M1 , OR10J3 , OR13G1 , OR2B3 , OR2J3 , OR14J1 , OR10C1 , OR2A2 , OR4F29 ,