Mono ADP-ribosylation of transducin catalyzed by rod outer segment extract

FEBS Lett. 1992 Sep 14;309(3):394-8. doi: 10.1016/0014-5793(92)80814-w.


Transducin is the retinal rod outer segment (ROS)-specific G protein coupling the photoexcited rhodopsin to cyclic GMP-phosphodiesterase. The alpha 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 [alpha-32P]nicotinamide adenine dinucleotide (NAD+), the alpha and beta subunits of transducin were found to be radiolabeled. The labeling was decreased by snake venom phosphodiesterase I (PDE I). The modification was shown to be mono ADP-ribosylation by analyses on thin layer chromatography of the PDE I-hydrolyzed products which revealed only 5'AMP residues. In addition we report that sodium nitroprusside activates the ADP-ribosylation of transducin.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Diphosphate / metabolism*
  • Chromatography, Thin Layer
  • Electrophoresis, Polyacrylamide Gel
  • Ribose / metabolism*
  • Rod Cell Outer Segment / metabolism*
  • Transducin / metabolism*


  • Adenosine Diphosphate
  • Ribose
  • Transducin