Requirement of ADP-ribosylation for the pertussis toxin-induced alteration in electrophoretic mobility of G-proteins

Sandra C. Roerig, Horace H Loh, Ping-Yee Law

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6 Scopus citations

Abstract

Pertussis toxin (PTX) catalyzes the ADP-ribosylation of the α-subunit of GTPbinding proteins (G-proteins) in the presence of NAD+. Pertussis toxin also decreases the electrophoretic mobility of the a-subunit on urea SDS PAGE. This effect of PTX has been suggested to be a property of the toxin different from its ability to catalyze ADP-ribosylation. However, the present report provides evidence to the contrary; ie, this mobility shift required the ADP-ribosylation of α-subunits. This conclusion was based on: (1) in the presence of increasing concentrations of NAD+ (0.026-1.3 μM), there was a linear increase in the formation of the slower migrating α-subunit as measured by immunoblotting with selective antisera, (2) addition of NADase to the incubation mixture completely eliminated the formation of this protein, and (3) increasing concentrations of nicotinamide (50-250 mM), which inhibits ADP-ribosylation, decreased the amount of the slower migrating a-subunit. Thus, in addition to PTX, NAD+ was required for the mobility shift and the slower migrating a-subunit is likely the ADP-ribosylated form.

Original languageEnglish (US)
Pages (from-to)1227-1232
Number of pages6
JournalBiochemical and Biophysical Research Communications
Volume180
Issue number3
DOIs
StatePublished - Nov 14 1991

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