Achromatopsia-associated mutation in the human cone photoreceptor cyclic nucleotide-gated channel CNGB3 subunit alters the ligand sensitivity and pore properties of heteromeric channels

Changhong Peng; Elizabeth D Rich; Michael D Varnum

doi:10.1074/jbc.M305102200

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Achromatopsia-associated mutation in the human cone photoreceptor cyclic nucleotide-gated channel CNGB3 subunit alters the ligand sensitivity and pore properties of heteromeric channels

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Achromatopsia-associated mutation in the human cone photoreceptor cyclic nucleotide-gated channel CNGB3 subunit alters the ligand sensitivity and pore properties of heteromeric channels

Changhong Peng, Elizabeth D Rich and Michael D Varnum

The Journal of biological chemistry, Vol.278(36), pp.34533-34540

09/05/2003

DOI: https://doi.org/10.1074/jbc.M305102200

Handle:

https://hdl.handle.net/2376/116015

PMID: 12815043

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Abstract

Potassium - metabolism

Green Fluorescent Proteins

Ion Channels

Humans

Electrophysiology

Molecular Sequence Data

RNA, Messenger - metabolism

Recombinant Fusion Proteins - metabolism

Color Vision Defects - genetics

Dose-Response Relationship, Drug

Diltiazem - pharmacology

Cell Membrane - metabolism

Cyclic AMP - metabolism

Dimerization

Protein Structure, Tertiary

Recombinant Proteins - metabolism

Amino Acid Sequence

Oocytes - metabolism

Xenopus laevis

Photoreceptor Cells - chemistry

Calcium Channel Blockers - pharmacology

Sequence Homology, Amino Acid

Microscopy, Confocal

Animals

Cyclic GMP - metabolism

Models, Biological

Ligands

Kinetics

Mutation

Cyclic Nucleotide-Gated Cation Channels

Retinal Cone Photoreceptor Cells - metabolism

Luminescent Proteins - metabolism

Cone photoreceptor cyclic nucleotide-gated (CNG) channels are thought to form by assembly of two different subunit types, CNGA3 and CNGB3. Recently, mutations in the gene encoding the CNGB3 subunit have been linked to achromatopsia in humans. Here we describe the functional consequences of two achromatopsia-associated mutations in human CNGB3 (hCNGB3). Co-expression in Xenopus oocytes of human CNGA3 (hCNGA3) subunits with hCNGB3 subunits containing an achromatopsia-associated mutation in the S6 transmembrane domain (S435F) generated functional heteromeric channels that exhibited an increase in apparent affinity for both cAMP and cGMP compared with wild type heteromeric channels. In contrast, co-expression of a presumptive null mutation of hCNGB3 (T383f.s.Delta C) with hCNGA3 produced channels with properties indistinguishable from homomeric hCNGA3 channels. The effect of hCNGB3 S435F subunits on cell-surface expression of green fluorescent protein-tagged hCNGA3 subunits and of non-tagged hCNGA3 subunits on surface expression of green fluorescent protein-hCNGB3 S435F subunits were similar to those observed for wild type hCNGB3 subunits, suggesting that the mutation does not grossly disturb subunit assembly or plasma membrane targeting. The S435F mutation was also found to produce changes in the pore properties of the channel, including decreased single channel conductance and decreased sensitivity to block by l-cis-diltiazem. Overall, these results suggest that the functional properties of cone CNG channels may be altered in patients with the S435F mutation, providing evidence supporting the pathogenicity of this mutation in humans. Thus, achromatopsia may arise from a disturbance of cone CNG channel gating and permeation or from the absence of functional CNGB3 subunits.

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Title: Achromatopsia-associated mutation in the human cone photoreceptor cyclic nucleotide-gated channel CNGB3 subunit alters the ligand sensitivity and pore properties of heteromeric channels
Creators: Changhong Peng - Department of Veterinary and Comparative Anatomy, Pharmacology, and Physiology and Program in Neuroscience, Washington State University, Pullman, Washington 99164-6520, USA
Elizabeth D Rich
Michael D Varnum
Publication Details: The Journal of biological chemistry, Vol.278(36), pp.34533-34540
Academic Unit: Integrative Physiology and Neuroscience, Department of
Publisher: United States
Grant note: EY12836 / NEI NIH HHS
Identifiers: 99900548061301842
Language: English
Resource Type: Journal article