[Effect of bacterial toxins on the GTPase activity of transducin from bovine rod outer segments].
The effects of choleragen- and pertussis toxin (PT)-induced ADP-ribosylation on the GTP-binding protein transducin (TD) from retinal rod outer segments (ROS) have been studied. It has been shown that both toxins cause inhibition of the TD GTPase activity. PT inhibited the GTPase by 30-40% in "native" ROS and by 70-80% in homogeneous TD. Choleragen, in contrast with PT, had no effect on the GTPase activity of homogeneous TD, but was as effective as PT in membrane preparations. The effects of both toxins on the GTPase activity of TD were found to be dependent on the chemical structure of the guanyl nucleotide present in the vehicle. The data obtained suggest that PT and choleragen differ in their specificity for the TD-guanyl nucleotide complex. The former can interact with free TD as well as with the TD-GDP complex, while the latter affects only the TD-GTP complex.
D000818:Animals; D001427:Bacterial Toxins / Q000494:pharmacology*; D002417:Cattle; D002772:Cholera Toxin / Q000494:pharmacology; D020558:GTP Phosphohydrolases / Q000037:antagonists & inhibitors*; D019204:GTP-Binding Proteins / Q000037:antagonists & inhibitors*; D006150:Guanine Nucleotides / Q000378:metabolism; D066298:In Vitro Techniques; D008565:Membrane Proteins / Q000037:antagonists & inhibitors*; D009243:NAD / Q000378:metabolism; D037342:Pertussis Toxin; D010744:Phosphoric Monoester Hydrolases / Q000037:antagonists & inhibitors*; D010786:Photoreceptor Cells / Q000201:enzymology*; D012374:Rod Cell Outer Segment / Q000201:enzymology* / Q000378:metabolism; D013379:Substrate Specificity; D015293:Transducin; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D001427:Bacterial Toxins; D006150:Guanine Nucleotides; D008565:Membrane Proteins; D010566:Virulence Factors, Bordetella; D009243:NAD; D002772:Cholera Toxin; D037342:Pertussis Toxin; D010744:Phosphoric Monoester Hydrolases; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins; D015293:Transducin
Vliianie bakterial'nykh toksinov na GTPaznuiu aktivnost' transdutsina naruzhnykh segmentov palochek setchatki byka.