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Strategic Screening and Characterization of the Visual GPCR-mini-G Protein Signaling Complex for Successful Crystallization
Published on: March 16, 2020
Characterization of human GRK7 as a potential cone opsin kinase
C K Chen1, K Zhang, J Church-Kopish
1Department of Ophthalmology and Visual Sciences, Moran Eye Center, University of Utah Health Science Center, Salt Lake City, UT 84112-5330, USA. jason.chen@hmbg.utah.edu
Molecular Vision
|January 5, 2002
Summary
Human GRK7, found in cone outer segments, may explain normal photopic vision in patients with defective GRK1. Mouse cones lack GRK7, relying solely on GRK1 for visual pigment regulation.
Area of Science:
- Ophthalmology
- Molecular Biology
- Genetics
Background:
- G protein-coupled receptor kinase 1 (GRK1) deficiency causes severe cone phototransduction defects in mice.
- Human patients with GRK1 defects show normal photopic vision, indicating a different mechanism.
Purpose of the Study:
- Investigate the role of GRK7, a human GRK family ortholog, in photopic vision.
- Understand the differential roles of GRK1 and GRK7 in mouse and human cone function.
Main Methods:
- Bioinformatic analysis to identify human GRK7.
- RT-PCR to isolate human and bovine GRK7 cDNAs.
- Recombinant GRK7 expression and phosphorylation assays.
- Immunoblotting and immunocytochemistry for GRK7 expression and localization.
Main Results:
- Human GRK7 gene located on chromosome 3q21; expressed exclusively in human retina, specifically in cone outer segments.
- Recombinant human GRK7 phosphorylates rhodopsin in a light-dependent manner.
- GRK1 and GRK7 are co-expressed in human cones, while mouse GRK7 is not expressed in mouse photoreceptors.
Conclusions:
- Human GRK7 in cone outer segments likely compensates for GRK1 defects, ensuring normal photopic vision.
- Absence of GRK7 in mouse cones suggests their sole reliance on GRK1 for visual pigment regulation.
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