Second messenger, cAMP, causes the opening of cation-selective cyclic nucleotide-gated (CNG) channels and depolarization of the neuron (olfactory sensory neurons, OSNs). CNGA4 is the modulatory subunit of this channel which is known to play a central role in the transduction of odorant signals and subsequent adaptation. By accelerating the calcium-mediated negative feedback in olfactory signaling it allows rapid adaptation to odor stimulation and extends its range of odor detection (By similarity). Calcium-calmodulin exerts its inhibitory effect in cAMP sensitivity by binding to IQ-like motif of CNGA4 and preferably binds to the channel in the closed state. Inhibition by PIP3 of the CNG channel probably occurs via CGNA2 binding. Heterotetramer composed of two subunits of CNGA2, one of CNGA4 and one of CNGB1b. The complex forms the cyclic nucleotide-gated (CNG) channel of olfactory sensory neurons. The C-terminal coiled-coil domain mediates trimerization of CNGA subunits. Belongs to the cyclic nucleotide-gated cation channel (TC 1.A.1.5) family. CNGA4 subfamily. Extended N-terminus.