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Binding of inositol phosphates to arrestin
Author(s) -
Palczewski Krzysztof,
Pulvermüller Alexander,
Buczylko Janina,
Gutmann Caroline,
Hofmann Klaus Peter
Publication year - 1991
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(91)81416-6
Subject(s) - inositol , inositol phosphate , chemistry , arrestin , biochemistry , biophysics , biology , receptor , g protein coupled receptor
Arrestin binds to phosphorylated rhodopsin in its light‐activated form (metarhodopsin II), blocking thereby its interaction with the G‐protein, transducin. In this study, we show that highly phosphorylated forms of inositol compete against the arrestin‐rhodopsin interaction. Competition curves and direct binding assays with free arrestin consistently yield affinities in the micromolar range; for example, inositol 1,3,4,5‐tetrakisphosphate (InP 4 ) and inositol hexakisphosphate (InP 6 bind to arrestin with dissociation constants of 12 μM and 5 μM, respectively. Only a small control amount of inositol phosphates is bound, when arrestin interacts with phosphorylated rhodopsin. This argues for a release of bound inositol phosphates by interaction with rhodopsin. Transducin, rhodopsin kinase, or cyclic GMP phosphodiesterase are not affected by inositol phosphates. These observations open a new way to purify arrestin and to inhibit its interaction with rhodopsin. Their physiological significance deserves further investigation.