Stereospecific modulation of dimeric rhodopsin.

Area of Science:

• Biochemistry
• Molecular Biology
• Vision Science

Background:

• G protein-coupled receptors (GPCRs) were traditionally viewed as monomers.
• Emerging evidence suggests GPCRs, including rhodopsin (Rh), can form dimers and oligomers.
• Rhodopsin is the only GPCR confirmed to exist as a dimer, but its functional role remains unclear.

Purpose of the Study:

• To identify small molecules that disrupt rhodopsin dimer contacts.
• To investigate the stereospecific effects of these compounds on rhodopsin function.
• To develop novel methods for targeting GPCR dimerization.

Main Methods:

• Cell-based high-throughput screening to identify potential disruptors.
• Separation of racemic mixtures into stereoisomers.
• UV-visible spectroscopy and intrinsic tryptophan fluorescence to assess binding.
• Electrophysiological recordings to evaluate effects on rod photoreceptor function.

Main Results:

• Econazole and sulconazole were identified as compounds disrupting Rh dimer contacts.
• R-econazole specifically modulates Meta III formation, quenches Trp265 fluorescence, and slows photoresponse kinetics.
• S-econazole reduces rod sensitivity without affecting kinetics.

Conclusions:

• This study presents novel compounds that specifically disrupt rhodopsin dimerization.
• It validates a new methodology for identifying GPCR-dimerization inhibitors.
• Findings shed light on the physiological role of rhodopsin dimerization in vision.