Abstract
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.
Publication types
-
Research Support, Non-U.S. Gov't
MeSH terms
-
ADP Ribose Transferases / metabolism
-
Adenosine Diphosphate Ribose / metabolism
-
Animals
-
Botulinum Toxins*
-
Cattle
-
Electrophoresis, Polyacrylamide Gel
-
Eye Proteins / metabolism*
-
GTP-Binding Proteins / metabolism*
-
Heterotrimeric GTP-Binding Proteins*
-
Light
-
Membrane Proteins / metabolism*
-
Molecular Weight
-
Pertussis Toxin
-
Retina / metabolism
-
Retinal Pigments / metabolism*
-
Rhodopsin / metabolism*
-
Transducin
-
Virulence Factors, Bordetella / metabolism
Substances
-
Eye Proteins
-
GNAT1 protein, human
-
Membrane Proteins
-
Retinal Pigments
-
Virulence Factors, Bordetella
-
Adenosine Diphosphate Ribose
-
Rhodopsin
-
ADP Ribose Transferases
-
exoenzyme C3, Clostridium botulinum
-
Pertussis Toxin
-
Botulinum Toxins
-
GTP-Binding Proteins
-
Heterotrimeric GTP-Binding Proteins
-
Transducin