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Light‐induced binding of 48‐kDa protein to photoreceptor membranes is highly enhanced by phosphorylation of rhodopsin
Author(s) -
Kühn H.,
Hall S.W.,
Wilden U.
Publication year - 1984
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(84)81221-1
Subject(s) - rhodopsin , phosphorylation , gtp' , protein kinase a , biophysics , biochemistry , binding protein , microbiology and biotechnology , protein phosphorylation , chemistry , biology , retinal , enzyme , gene
The 48‐kDa protein, a major protein of rod photoreceptor cells, is soluble in the dark but associates with the disk membranes when some (5–10%) of their rhodopsin has absorbed light and if this rhodopsin is additionally phosphorylated by ATP and rhodopsin kinase. If rhodopsin has been phosphorylated and regenerated prior to the protein binding experiment, the binding of 48‐kDa protein depends on light but no longer on the presence of ATP. Another photoreceptor protein, GTP‐binding protein, associates with both phosphorylated and unphosphorylated rhodopsin upon illumination. Excess GTP‐binding protein thereby displaces 48‐kDa protein from phosphorylated disks; this indicates competition between these two proteins for binding sites on illuminated phosphorylated rhodopsin molecules.