7o4h
From Proteopedia
The structure of the native CNGA1/CNGB1 CNG channel from retinal rods
Structural highlights
FunctionCNGA1_BOVIN Visual signal transduction is mediated by a G-protein coupled cascade using cGMP as second messenger. This protein can be activated by cGMP which leads to an opening of the cation channel and thereby causing a depolarization of rod photoreceptors. Publication Abstract from PubMedIn rod photoreceptors of the retina, the cyclic nucleotide-gated (CNG) channel is composed of three CNGA and one CNGB subunits, and it closes in response to light activation to generate an electrical signal that is conveyed to the brain. Here we report the cryo-EM structure of the closed state of the native rod CNG channel isolated from bovine retina. The structure reveals differences between CNGA1 and CNGB1 subunits. Three CNGA1 subunits are tethered at their C terminus by a coiled-coil region. The C-helix in the cyclic nucleotide-binding domain of CNGB1 features a different orientation from that in the three CNGA1 subunits. The arginine residue R994 of CNGB1 reaches into the ionic pathway and blocks the pore, thus introducing an additional gate, which is different from the central hydrophobic gate known from homomeric CNGA channels. These results address the long-standing question of how CNGB1 subunits contribute to the function of CNG channels in visual and olfactory neurons. The structure of the native CNGA1/CNGB1 CNG channel from bovine retinal rods.,Barret DCA, Schertler GFX, Kaupp UB, Marino J Nat Struct Mol Biol. 2022 Jan;29(1):32-39. doi: 10.1038/s41594-021-00700-8. Epub , 2021 Dec 30. PMID:34969975[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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