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Mutation of a conserved proline disrupts the retinal-binding pocket of the X-linked cone opsins

H Ostrer1, M A Kazmi

  • 1Human Genetics Program, Department of Pediatrics, New York University Medical Center, New York, NY 10016, USA. ostreh01@mcrcr6.med.nyu.edu

Molecular Vision
|April 4, 1998
PubMed
Abstract

Insights

Disrupting a key proline in green cone opsin impairs visual pigment function and transducin activation, potentially causing color vision deficiency unrelated to spectral shifts.

Area of Science:

  • Molecular Biology
  • Vision Science
  • Biochemistry

Background:

  • Cone opsins are crucial for color vision.
  • A conserved proline residue is vital for opsin function.

Purpose of the Study:

  • To investigate the impact of disrupting a conserved proline in green cone opsin.
  • To assess effects on light-activated isomerization, transducin activation, protein accumulation, glycosylation, and transport.

Main Methods:

  • Established stable EBNA-293 cell lines with wild-type and mutant (P307L) green opsin cDNA.
  • Analyzed protein function using spectroscopy, transducin activation assays, Western blotting, and immunocytochemistry.

Main Results:

  • The P307L mutation significantly reduced light absorption and transducin activation.
  • Protein glycosylation and cell membrane transport remained unaffected.
  • A minor decrease in opsin accumulation was observed but did not fully explain the functional deficit.

Conclusions:

  • Cone opsin visual pigment formation requires retinal binding within a hydrophobic pocket.
  • Disrupting a conserved proline near the retinal binding site can cause color vision deficiency.
  • This deficiency is independent of alterations in the photopigment's spectral properties.

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