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Updated: May 17, 2026
08:21
Monitoring GPCR-β-arrestin1/2 Interactions in Real Time Living Systems to Accelerate Drug Discovery
Published on: June 28, 2019
Conformation of receptor-bound visual arrestin
Miyeon Kim1, Sergey A Vishnivetskiy, Ned Van Eps
1Jules Stein Eye Institute, Department of Ophthalmology, University of California, Los Angeles, CA 90095, USA.
Summary
Arrestin-1 binding to phosphorylated rhodopsin (P-Rh*) restructures its loops, not domains. This visual arrestin conformational change, revealed by spin labeling, facilitates G-protein signaling termination.
Area of Science:
- Molecular and Cellular Biology
- Biophysics
- Structural Biology
Background:
- Arrestin-1 (visual arrestin) is crucial for terminating G-protein signaling by binding to light-activated phosphorylated rhodopsin (P-Rh*).
- Understanding arrestin-1's conformational changes upon receptor binding is key to elucidating its signaling termination mechanism.
Purpose of the Study:
- To map the conformational dynamics of arrestin-1 during its interaction with phosphorylated rhodopsin (P-Rh*).
- To investigate the structural rearrangements in arrestin-1 upon binding to P-Rh* using biophysical techniques.
Main Methods:
- Site-directed spin labeling of arrestin-1.
- Double electron-electron resonance (DEER) spectroscopy to measure interspin distances.
- Analysis of conformational changes upon binding to light-activated phosphorylated rhodopsin (P-Rh*).
Main Results:
- Contrary to the 'clam-shell' model, the N and C domains of arrestin-1 showed minimal positional change upon P-Rh* binding.
- A key 'finger loop' (residues 67-79) moved towards P-Rh* but remained partially folded.
- An unexpected outward movement of a loop near residue 139, and smaller movements in loops at residues 157 and 344, were observed, facilitating P-Rh* binding and indicating high loop flexibility.
Conclusions:
- Arrestin-1 binding to P-Rh* involves significant loop rearrangements rather than a complete domain closure.
- The observed loop movements, particularly around residue 139, are critical for P-Rh* binding and signal termination.
- Flexible loops in arrestin-1 maintain plasticity in both free and bound states, suggesting dynamic conformational adaptability.
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