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Mono ADP‐ribosylation of transducin catalyzed by rod outer segment extract
Author(s) -
Ehret-Hilberer Sylviane,
Nullans Gërard,
Aunis Dominique,
Virmaux Noélle
Publication year - 1992
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(92)80814-w
Subject(s) - transducin , adp ribosylation , chemistry , biophysics , catalysis , biochemistry , biology , g protein , enzyme , nad+ kinase , receptor
Transducin is the retinal rod outer segment (ROS)‐specific G protein coupling the photoexcited rhodopsin to cyclic GMP‐phosphodiesterase. The α subunit of transducin is known to be ADP‐ribosylated by bacterial toxins. We investigated the possibility that transducin is modified in vitro by an endogenous ADP‐ribosyltransferase activity. By using either ROS, cytosolic extract of ROS or purified transducin in the presence of [α??P]nicotinamide adenine dinucleotide (NAD*), the α and β subunits of transducin were found to be radiolabeled, The labeling was decreased by snake venom phosphodiesterase I (PDE 1). The modification was shown to be mono ADP‐ribosylation by analyses on thin layer chromatography of the PDE 1‐hydrolyzed products which revealed only 5′AMP residues. In addition we report that sodium nitroprusside activates the ADP‐ribosylation of transducin.