Cyclic nucleotide–gated ion channel

Cyclic nucleotide–gated (CNG) ion channels are ion channels that function in response to the binding of cyclic nucleotides. CNG channels are nonselective cation channels that are found in the membranes of various tissue and cell types, and are significant in sensory transduction as well as cellular development.

Structure

CNG channels are composed of a tetramer of subunits, each containing six membrane-spanning segments (S1-S6). The pore region is formed by the S5 and S6 segments and the connecting loop. The S4 segment acts as the voltage sensor. The C-linker region, located between the S6 segment and the cyclic nucleotide-binding domain (CNBD), is critical for channel gating.

Function

CNG channels play a crucial role in signal transduction pathways. They are involved in the conversion of sensory information into electrical signals, particularly in vision and olfaction. In the retina, CNG channels are involved in phototransduction, the process by which light is converted into electrical signals. In olfactory sensory neurons, CNG channels mediate signal transduction for odor detection.

Clinical significance

Mutations in CNG channel genes have been associated with various diseases. For example, mutations in the genes encoding the alpha subunits of rod and cone CNG channels can lead to retinitis pigmentosa and achromatopsia, respectively.

See also

• Ion channel
• Cyclic nucleotide
• Signal transduction
• Retinitis pigmentosa
• Achromatopsia