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Pathway : Olfactory transduction

Identifier  04740 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 cAMPLonger exposure to odorants can stimulate particulate guanylyl cyclase in cilia to produce cGMP and activate PKG, leading to a further increase in amount and duration of intracellular cAMP levels, which may serve to convert inactive forms of protein kinase A PKA2 to active forms PKA As part of a feedback loop, PKA can inhibit the activation of particulate guanylyl cyclase

1 Data Sets

1403 Genes

0 Proteins