کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1957301 1057878 2005 10 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Reduction of All-trans Retinal to All-trans Retinol in the Outer Segments of Frog and Mouse Rod Photoreceptors
موضوعات مرتبط
علوم زیستی و بیوفناوری بیوشیمی، ژنتیک و زیست شناسی مولکولی زیست شیمی
پیش نمایش صفحه اول مقاله
Reduction of All-trans Retinal to All-trans Retinol in the Outer Segments of Frog and Mouse Rod Photoreceptors
چکیده انگلیسی

The first step in the Visual Cycle, the series of reactions that regenerate the vertebrate visual pigment rhodopsin, is the reduction of all-trans retinal to all-trans retinol, a reaction that requires NADPH. We have used the fluorescence of all-trans retinol to study this reduction in living rod photoreceptors. After the bleaching of rhodopsin, fluorescence (excitation, 360 nm; emission, 457 or 540 nm) appears in frog and wild-type mouse rod outer segments reaching a maximum in 30–60 min at room temperature. With this excitation and emission, the mitochondrial-rich ellipsoid region of the cells shows strong fluorescence as well. Fluorescence measurements at different emission wavelengths establish that the outer segment and ellipsoid signals originate from all-trans retinol and reduced pyridine nucleotides, respectively. Using outer segment fluorescence as a measure of all-trans retinol formation, we find that in frog rod photoreceptors the NADPH necessary for the reduction of all-trans retinal can be supplied by both cytoplasmic and mitochondrial metabolic pathways. Inhibition of the reduction reaction, either by retinoic acid or through suppression of metabolic activity, reduced the formation of retinol. Finally, there are no significant fluorescence changes after bleaching in the rod outer segments of Rpe65−/− mice, which lack 11-cis retinal.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: - Volume 88, Issue 3, March 2005, Pages 2278–2287
نویسندگان
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