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The gecko visual pigments. The behavior of opsin
The Journal of General Physiology
|May 1, 1979
Summary
Tokay gecko visual pigment exhibits typical vertebrate stereospecificity. Regeneration with different retinals and chloride addition confirms its unique chloride-dependent spectral tuning and rapid regeneration kinetics.
Area of Science:
- Biochemistry
- Molecular Biology
- Vision Science
Background:
- Vertebrate visual pigments are crucial for light detection.
- The spectral properties of visual pigments are influenced by their environment, including ion concentrations.
- Understanding visual pigment mechanisms provides insights into evolution and molecular function.
Purpose of the Study:
- To investigate the stereospecificity and spectral properties of the Tokay gecko's 521-pigment.
- To examine the regeneration process and chloride dependence of this visual pigment.
- To explore the implications of these findings for phylogenetic and molecular studies.
Main Methods:
- Extraction and characterization of the 521-pigment from Tokay gecko retina.
- Spectrophotometric analysis of pigment states (chloride-depleted vs. normal).
- In vitro regeneration assays using different retinal isomers (11-cis and 9-cis) and chloride.
- Assessment of pigment response to sulfhydryl poison (p-hydroxymercuribenzoate).
Main Results:
- The 521-pigment demonstrated typical vertebrate visual pigment stereospecificity in both chloride-depleted and normal states.
- Regeneration occurred rapidly (<5 min) with both 11-cis- and 9-cis-retinals, yielding chloride-depleted, blue-shifted pigments.
- Chloride addition restored the normal spectral position, and chloride-deficient opsin also responded to chloride.
- Both native and regenerated chloride-depleted pigments showed blue shifts with p-hydroxymercuribenzoate, reversible by chloride addition.
Conclusions:
- The Tokay gecko 521-pigment exhibits chloride-dependent spectral tuning and rapid regeneration, characteristic of vertebrate visual pigments.
- The pigment's unique properties offer insights into the evolution of visual systems.
- These findings contribute to understanding the molecular mechanisms underlying visual pigment function and spectral tuning.
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