The function of ENSG00000144191 (CNGA3, cyclic nucleotide gated channel subunit alpha 3) is as follows. Pore-forming subunit of the cone cyclic nucleotide-gated channel. Mediates cone photoresponses at bright light converting transient changes in intracellular cGMP levels into electrical signals. In the dark, cGMP levels are high and keep the channel open enabling a steady inward current carried by Na(+) and Ca(2+) ions that leads to membrane depolarization and neurotransmitter release from synaptic terminals. Upon photon absorption cGMP levels decline leading to channel closure and membrane hyperpolarization that ultimately slows neurotransmitter release and signals the presence of light, the end point of the phototransduction cascade (PubMed:10888875, PubMed:12815043, PubMed:34969976, PubMed:37463923). Pore-forming subunit of the gustatory cyclic nucleotide-gated channel. In the taste buds, may sense oral extracellular pH and conduct ion currents that modulate the excitability of taste cells (By similarity). Conducts cGMP- and cAMP-gated ion currents, with permeability for monovalent and divalent cations (By similarity) (PubMed:12815043). {ECO:0000250|UniProtKB:Q29441, ECO:0000250|UniProtKB:Q9ER33, ECO:0000269|PubMed:10888875, ECO:0000269|PubMed:12815043, ECO:0000269|PubMed:34969976, ECO:0000269|PubMed:37463923}.