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Binding of More Than One Retinoid to Visual Opsins
- Source :
- Biophysical Journal. 99:2366-2373
- Publication Year :
- 2010
- Publisher :
- Elsevier BV, 2010.
-
Abstract
- Visual opsins bind 11-cis retinal at an orthosteric site to form rhodopsins but increasing evidence suggests that at least some are capable of binding an additional retinoid(s) at a separate, allosteric site(s). Microspectrophotometric measurements on isolated, dark-adapted, salamander photoreceptors indicated that the truncated retinal analog, β-ionone, partitioned into the membranes of green-sensitive rods; however, in blue-sensitive rod outer segments, there was an enhanced uptake of four or more β-ionones per rhodopsin. X-ray crystallography revealed binding of one β-ionone to bovine green-sensitive rod rhodopsin. Cocrystallization only succeeded with extremely high concentrations of β-ionone and binding did not alter the structure of rhodopsin from the inactive state. Salamander green-sensitive rod rhodopsin is also expected to bind β-ionone at sufficiently high concentrations because the binding site is present on its surface. Therefore, both blue- and green-sensitive rod rhodopsins have at least one allosteric binding site for retinoid, but β-ionone binds to the latter type of rhodopsin with low affinity and low efficacy.
- Subjects :
- Rhodopsin
Opsin
genetic structures
medicine.drug_class
Allosteric regulation
Spectroscopy, Imaging, and Other Techniques
Biophysics
Urodela
Plasma protein binding
Crystallography, X-Ray
Retinoids
03 medical and health sciences
chemistry.chemical_compound
0302 clinical medicine
Retinal Rod Photoreceptor Cells
medicine
Animals
Retinoid
Binding site
030304 developmental biology
0303 health sciences
biology
Retinal
Rod Cell Outer Segment
Crystallography
Membrane
chemistry
Microspectrophotometry
biology.protein
Cattle
sense organs
Norisoprenoids
030217 neurology & neurosurgery
Protein Binding
Subjects
Details
- ISSN :
- 00063495
- Volume :
- 99
- Database :
- OpenAIRE
- Journal :
- Biophysical Journal
- Accession number :
- edsair.doi.dedup.....da5f8af56ccdf6596a03734b6801b25e
- Full Text :
- https://doi.org/10.1016/j.bpj.2010.08.003