CNGA4

CNGA4, or cyclic nucleotide-gated channel subunit alpha-4, is a protein that is part of the cyclic nucleotide-gated (CNG) channel family. The CNGA4 gene encodes this subunit in humans and other mammals. CNG channels are non-selective cation channels that open in response to cyclic nucleotides such as cGMP and cAMP, mediating depolarizing currents in sensory neurons.

CNGA4 functions as an auxiliary or modulatory subunit in heteromeric CNG channels. It typically does not form functional channels on its own but co-assembles with other CNGA and/or CNGB subunits to form functional channels. Through this assembly, CNGA4 modulates channel properties, including the apparent affinity for cyclic nucleotides, gating kinetics, and trafficking to the plasma membrane. It contributes to the tuning of sensory signals rather than encoding primary stimulus detection by itself.

Expression of CNGA4 has been detected in tissues involved in olfactory and visual transduction, particularly the retina and olfactory epithelium in humans and other mammals. In photoreceptors, CNG channels link the light-activated phototransduction cascade to electrical signaling by controlling Na+ and Ca2+ influx in response to intracellular cGMP levels. In olfactory receptor neurons, CNG channels participate in odorant signal transduction following receptor-stimulated increases in cyclic nucleotide concentrations.

Mutations or variants in CNGA4 have been explored for potential roles in sensory disorders, but robust associations remain limited. Ongoing research seeks to clarify the precise contribution of CNGA4 to channel assembly, gating modulation, and the overall physiology of olfactory and visual systems.