Characterization of human GRK7 as a potential cone opsin kinase

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Publication Type Journal Article
School or College School of Medicine
Department Ophthalmology; Neurobiology & Anatomy
Creator Baehr, Wolfgang; Zhang, Kang
Other Author Chen, C K; Church-Kopish, J; Huang, W; Zhang, H; Chen, Y J; Frederick, J M
Title Characterization of human GRK7 as a potential cone opsin kinase
Date 2001
Description PURPOSE: Homozygous inactivation of the mouse gene for GRK1 (G protein-coupled receptor kinase 1, or rhodopsin kinase) causes severe defects in the recovery of cone phototransduction. However, electroretinographic (ERG) analyses of human oguchi patients with defective GRK1 alleles showed normal or slightly abnormal photopic responses. It remains unclear why the loss of GRK1 yields such different phenotypes in the recovery of mouse and human cones. We examined the localization and enzyme activity of GRK7, the human ortholog of the seventh member of the GRK family, in an attempt to understand its potential role in photopic vision. METHODS: Bioinformatic approaches were used to identify the human GRK7 gene. Human and bovine GRK7 cDNAs were isolated by RT-PCR. Recombinant GRK7, expressed in insect cells, was used to phosphorylate activated rhodopsin. Antibodies raised against GRK7 peptides were used to examine the retina specific expression of GRK7 by immunoblotting and its subcellular localization by immunocytochemistry. RESULTS: The human GRK7 gene is located on chromosome 3q21, spans at least 10 Kb and consists of 4 exons. In human, GRK7 is expressed exclusively in the retina and is found in all retinal neurons, and specifically, in cone outer segments. Recombinant human GRK7 catalyzes rhodopsin phosphorylation in a light dependent manner. We provide evidence that GRK1 and GRK7 are co-expressed in human cones. In contrast, mouse GRK7 is expressed in many tissues including retina where photoreceptors apparently do not express GRK7. CONCLUSIONS: The presence of GRK7 in human, but not in mouse, cone outer segments suggests that GRK7 may function to provide the normal photopic vision reported by oguchi patients with a defective GRK1 gene. The absence of GRK7 expression in cone outer segments of mice is consistent with the notion that mouse cones rely solely on GRK1 to shutoff cone visual pigments.
Type Text
Publisher Molecular Vision
First Page 305
Last Page 313
Subject Amino Acid Sequence; Chromosomes, Human, Pair 3; Fluorescent Antibody Technique, Indirect
Subject MESH Cones (Retina); Protein Kinases; Eye Proteins
Language eng
Bibliographic Citation Chen CK, Zhang K, Church-Kopish J, Huang W, Zhang H, Chen YJ, Frederick JM, Baehr W. (2001). Characterization of human GRK7 as a potential cone opsin kinase. Mol Vis, 7, 305-13
Rights Management (c) Molecular Vision
Format Medium application/pdf
Identifier ir-main,1728
ARK ark:/87278/s6r78zzx
Setname ir_uspace
Date Created 2012-06-13
Date Modified 2021-05-06
ID 707488
Reference URL
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