8bx7

Structural highlights

Function

CNGB1_BOVIN Pore-forming subunit of the rod cyclic nucleotide-gated channel. Mediates rod photoresponses at dim 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:10352032, PubMed:21878911, PubMed:34969975, PubMed:37011209). Pore-forming subunit of the olfactory cyclic nucleotide-gated channel. Operates in the cilia of olfactory sensory neurons where chemical stimulation of the odorant is converted to an electrical signal. Mediates odorant-induced cAMP-dependent Ca(2+) influx triggering neuron depolarization. The rise of intracellular Ca(2+) levels potentiates the olfactory response by activating Ca(2+)-dependent Cl(-) channels, but it also serves as a negative feedback signal to desensitize the channel for rapid adaptation to odorants (By similarity). Conducts cGMP- and cAMP-gated ion currents, with permeability for monovalent and divalent cations. The selectivity for Ca(2+) over Na(+) increases with cGMP concentrations, whereas the selectivity among monovalent ions is independent of the cGMP levels (By similarity) (PubMed:10352032).[UniProtKB:A0A8I5ZN27][UniProtKB:Q9NQW8]^{[1] [2] [3] [4]}

See Also

• Ion channels 3D structures

References

1. ↑ Hackos DH, Korenbrot JI. Divalent cation selectivity is a function of gating in native and recombinant cyclic nucleotide-gated ion channels from retinal photoreceptors. J Gen Physiol. 1999 Jun;113(6):799-818. PMID:10352032 doi:10.1085/jgp.113.6.799
2. ↑ Shuart NG, Haitin Y, Camp SS, Black KD, Zagotta WN. Molecular mechanism for 3:1 subunit stoichiometry of rod cyclic nucleotide-gated ion channels. Nat Commun. 2011 Aug 30;2:457. doi: 10.1038/ncomms1466. PMID:21878911 doi:10.1038/ncomms1466
3. ↑ Barret DCA, Schertler GFX, Kaupp UB, Marino J. The structure of the native CNGA1/CNGB1 CNG channel from bovine retinal rods. Nat Struct Mol Biol. 2022 Jan;29(1):32-39. PMID:34969975 doi:10.1038/s41594-021-00700-8
4. ↑ Barret DCA, Schuster D, Rodrigues MJ, Leitner A, Picotti P, Schertler GFX, Kaupp UB, Korkhov VM, Marino J. Structural basis of calmodulin modulation of the rod cyclic nucleotide-gated channel. Proc Natl Acad Sci U S A. 2023 Apr 11;120(15):e2300309120. PMID:37011209 doi:10.1073/pnas.2300309120
5. ↑ Barret DCA, Schuster D, Rodrigues MJ, Leitner A, Picotti P, Schertler GFX, Kaupp UB, Korkhov VM, Marino J. Structural basis of calmodulin modulation of the rod cyclic nucleotide-gated channel. Proc Natl Acad Sci U S A. 2023 Apr 11;120(15):e2300309120. PMID:37011209 doi:10.1073/pnas.2300309120