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Infect. Immun., 03 1995, 825-832, Vol 63, No. 3
Y Xu and JT Barbieri
Pertussis toxin (PT)-catalyzed ADP-ribosylation of target proteins in
intact Chinese hamster ovary (CHO) cells was evaluated with an in vitro
ADP-ribosylation assay. In this assay, a postnuclear supernatant was
prepared from CHO cells and used as a source of PT-sensitive target
proteins for in vitro [32P[ADP-ribosylation. The postnuclear supernatant
contained three proteins that were ADP-ribosylated in vitro, with apparent
molecular masses of 50, 45, and 42 kDa. The 42- and 45-kDa proteins were
membrane associated, while the 50-kDa protein was soluble. Following PT
treatment of CHO cells, the 42- and 45-kDa proteins were not available for
in vitro ADP-ribosylation, while the soluble 50-kDa protein remained
available for in vitro ADP- ribosylation. The decrease in the availability
of the 42- and 45-kDa proteins to in vitro ADP-ribosylation was
proportional to the PT concentration and time of incubation with CHO cells.
Western immunoblot analysis showed that extracts from PT-treated CHO cells
and control CHO cells possessed equivalent amounts of two proteins that
were recognized by anti-Gi protein antiserum. The two proteins recognized
by anti-Gi protein antiserum from PT-treated cells migrated with higher
apparent molecular weights than the two proteins from control cells. This
was consistent with the in vivo ADP-ribosylation of the two proteins by
PT.(ABSTRACT TRUNCATED AT 250 WORDS)
Copyright © 1995, American Society for Microbiology
Pertussis toxin-mediated ADP-ribosylation of target proteins in Chinese hamster ovary cells involves a vesicle trafficking mechanism
Department of Microbiology, Medical College of Wisconsin, Milwaukee 53226.
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