ADP-ribosylation of transducin by pertussis toxin

Journal Article · Mon Nov 04 23:00:00 EST 1985 · J. Biol. Chem.; (United States)

OSTI ID:6085100

Watkins, P A; Burns, D L; Kanaho, Y; Liu, T Y; Hewlett, E L; Moss, J

Transducin, the guanyl nucleotide-binding regulatory protein of retinal rod outer segments that couples the photon receptor, rhodopsin, with the light-activated cGMP phosphodiesterase, can be resolved into two functional components, T alpha and T beta gamma. T alpha (39 kDa), which is (TSP)ADP-ribosylated by pertussis toxin and (TSP)NAD in rod outer segments and in purified transducin, was also labeled by the toxin after separation from T beta gamma (36 kDa and approximately 10 kDa); neither component of T beta gamma was a pertussis toxin substrate. Labeling of T alpha was enhanced by T beta gamma and was maximal at approximately 1:1 molar ratio of T alpha : T beta gamma. Limited proteolysis by trypsin of T alpha in the presence of guanyl-5'-yl imidodiphosphate (Gpp(NH)p) resulted in the sequential appearance of proteins of 38 and TS kDa. The amino terminus of both 38- and TS-kDa proteins was leucine, whereas that of T alpha could not be identified and was assumed to be blocked. The TS-kDa peptide was not a pertussis toxin substrate. Labeling of the 38-kDa protein was poor and was not enhanced by T beta gamma. Trypsin treatment of (TSP)ADP-ribosyl-T alpha produced a labeled 37-38-kDa doublet followed by appearance of radioactivity at the dye front. It appears, therefore, that, although the 38-kDa protein was poor toxin substrate, it contained the ADP-ribosylation site. Without rhodopsin, labeling of T alpha (in the presence of T beta gamma) was unaffected by Gpp(NH)p, guanosine 5'-O-(thiotriphosphate) (GTP gamma S), GTP, GDP, and guanosine 5'-O-(thiodiphosphate) (GDP beta S) but was increased by ATP. When photolyzed rhodopsin and T beta gamma were present, Gpp(NH)p and GTP gamma S decreased (TSP)ADP-ribosylation by pertussis toxin. Thus, pertussis toxin-catalyzed (TSP)ADP-ribosylation of T alpha was affected by nucleotides, rhodopsin and light in addition to T beta gamma.

• Research Organization: National Heart, Lung, and Blood Institute, Bethesda, MD
• OSTI ID: 6085100
• Journal Information: J. Biol. Chem.; (United States), Journal Name: J. Biol. Chem.; (United States) Vol. 25; ISSN JBCHA
• Country of Publication: United States
• Language: English

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59 BASIC BIOLOGICAL SCIENCES
ADP
ALDEHYDES
AMINO ACIDS
ANTIGENS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CARBOHYDRATES
CARBOXYLIC ACIDS
CATALYSTS
CHEMICAL REACTIONS
COENZYMES
DAYS LIVING RADIOISOTOPES
DECOMPOSITION
DISEASES
ELECTROMAGNETIC RADIATION
ENZYMES
HYDROLASES
INFECTIOUS DISEASES
ISOTOPE APPLICATIONS
ISOTOPES
LABELLING
LEUCINE
LIGHT NUCLEI
MATERIALS
METABOLISM
MONOSACCHARIDES
NAD
NUCLEI
NUCLEOTIDES
ODD-ODD NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PENTOSES
PEPTIDE HYDROLASES
PHOSPHATES
PHOSPHORUS 32
PHOSPHORUS COMPOUNDS
PHOSPHORUS ISOTOPES
PIGMENTS
PROTEINS
PROTEOLYSIS
RADIATIONS
RADIOISOTOPES
RHODOPSIN
RIBOSE
SACCHARIDES
SERINE PROTEINASES
TOXIC MATERIALS
TOXINS
TRACER TECHNIQUES
TRYPSIN
VISIBLE RADIATION