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The G-protein or GTP-binding protein binds to GTP when activated. Then a subunit of the g-protein signals the enzyme Adenylyl cyclase to begin synthesizing cAMP.

The olfactory receptor binds the olfactant (0dorant) to begin the transduction process. The receptor leads to the activation of the g-protein called Golf in the case of olfactory receptors.

The sodium channel is opened by cAMP. As the concentration of cAMP increases the channel opens more. This allows the influx of sodium (why influx?) and the depolarization of the olfactory receptor. Calcium also enters the membrane through the sodium channels and acts as a second messenger to open chloride channels. The concentration of chloride in olfactory receptors is unusual. The chloride reversal potential is positive to the resting level. So opening the chloride channels in this case causes the membrane to depolarize, adding to the effects of the sodiium channel

The chloride channel is opened by Ca acting as a second messenger. The chloride concentration is reversed in these receptors, putting the reversal potential at a postive value. Therefore, when the chloride channels open, the membrnae is depolarized. This depolarization acts in synergy with the depoarization due to sodium channel opening, enhancingt the olfractory response.

Click on the Names of Each of the Components of the Olfactory Transduction Cascade