Experimente zur lichtabhängigen Rhodopsin Phosphorylierung an Stäbchenaussensegment Suspensionen

Wilden, U.

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FZJ-2018-01758

Experimente zur lichtabhängigen Rhodopsin Phosphorylierung an Stäbchenaussensegment Suspensionen

Wilden, U. (Corresponding author)FZJ*

1981
Kernforschungsanlage Jülich, Verlag Jülich

Jülich : Kernforschungsanlage Jülich, Verlag, Berichte der Kernforschungsanlage Jülich 1741, 75 p. (1981)

Please use a persistent id in citations: http://hdl.handle.net/2128/17616

Report No.: Juel-1741

Abstract: 1. The light-dependent phosphorylation of frog and bovine rhodopsin was investigated under different conditions with suspensions of isolated rod outer segments. For both frog and bovinerhodopsin the average phosphorylation extent was found to be as high as 7,0 ± 0,3 mol phosphate per mol rhodopsin under optimal incubation conditions. The same result has been obtained with two independent methods of analysis. 2. Phosphorylated rhodopsin has been separated into rhodopsin fractions of different phosphorylation extents by means of ion exchange chromatography, in order td get information about the distribution of phosphorylation extents on different rhodopsin molecules within a population of known average phosphorylation extent. The distribution was found to be rather inhomogeneous. Rhodopsin sampIes of all average phosphorylation extents between 1 and 7 mol phosphate per mol rhodopsin were found to be mixtures of differently phosphorylated rhodopsins and unphosphorylated rhodopsin. Even at the maximum average phosphorylation extent of 7 mol phosphate per mol rhodopsin2-3 % of the rhodopsin remains unphosphorylated. It is shown that individual rhodopsin molecules are able to incorporate up to 9 phosphate residues. There is evidence for the existence of rhodopsin molecules of all phosphorylatioh extents between ° and 9 mol phosphate per mol of rhodopsin. 3. I have tried to find out if under more physiological conditions the initial velocity of phosphorylation is as slow as after bleaching of 100 % of the rhodopsin. The time course of phosphorylation is shown to be much faster with bleaching of only 13-23 % of rhodopsin; addition of kinase containing extract also accelerates the rate of phosphorylation. 4. Dephosphorylation experiments leaded to arelease of about 60 % of the phosphate incorporated. A possible role of rhodopsin phosphorylation in the regulationof light-dependent enzyme reactions is discussed.

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