Interaction of small G proteins with photoexcited rhodopsin.
Bovine rod outer segment (ROS) membranes contain in addition to the heterotrimeric G protein transducin, several small GTP-binding proteins (23-27 kDa). Furthermore, these membranes contain two substrate proteins (about 22 and 24 kDa) for botulinum C3 ADP-ribosyltransferase known to ADP-ribosylate small G proteins in any mammalian cell type studied so far. Most interestingly, [32P]ADP-ribosylation of ROS membrane small G proteins by C3 is regulated by light and guanine nucleotides in a manner similar to pertussis toxin-catalyzed [32P]ADP-ribosylation of the alpha-subunit of transducin. These findings suggest that not only the heterotrimeric G protein transducin but also the C3 substrate small G proteins present in ROS membranes interact with photoexcited rhodopsin and thus contribute to its signalling action.
Wieland
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Pharmakologisches Institut der Universität Heidelberg, FRG.
Ulibarri
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Aktories
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Gierschik
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Jakobs
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D036002:ADP Ribose Transferases / Q000378:metabolism; D000246:Adenosine Diphosphate Ribose / Q000378:metabolism; D000818:Animals; D001905:Botulinum Toxins; D002417:Cattle; D004591:Electrophoresis, Polyacrylamide Gel; D005136:Eye Proteins / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism*; D020962:Heterotrimeric GTP-Binding Proteins; D008027:Light; D008565:Membrane Proteins / Q000378:metabolism*; D008970:Molecular Weight; D037342:Pertussis Toxin; D012160:Retina / Q000378:metabolism; D012168:Retinal Pigments / Q000378:metabolism*; D012243:Rhodopsin / Q000378:metabolism*; D015293:Transducin; D010566:Virulence Factors, Bordetella / Q000378:metabolism
D005136:Eye Proteins; C034809:GNAT1 protein, human; D008565:Membrane Proteins; D012168:Retinal Pigments; D010566:Virulence Factors, Bordetella; D000246:Adenosine Diphosphate Ribose; D012243:Rhodopsin; D036002:ADP Ribose Transferases; C063007:exoenzyme C3, Clostridium botulinum; D037342:Pertussis Toxin; D001905:Botulinum Toxins; D019204:GTP-Binding Proteins; D020962:Heterotrimeric GTP-Binding Proteins; D015293:Transducin