ABSTRACT
Pertussis toxin produced by Bordetella pertussis bacteria was first introduced by Ui and his colleagues into research on signal transduction under the name islet-activating protein (lAP) in 1979, when a mechanism of the toxin-induced modification of insulin secretory responses in rat pancreatic islets was reported (Katada and Ui, 1979a,b). The action of lAP was soon proved to be due to the ADP-ribosylation of a 41-kDa membrane protein (Katada and Ui, 1982a), which was later identified as the a subunit of the inhibitory guanine nucleotide-binding regulatory component of adenylyl cyclase, Gi (Katada et al., 1984a). Since demonstration of the molecular mechanism of lAP, the toxin has been widely used as the best probe for identifying and analyzing major af3y-trimeric G proteins that are involved in a variety of membrane-bound receptor-induced signal transductions. The purpose of this review is to summarize representative results of successful applications of lAP to research on cell signaling, together with recent advances in the studies of lAP-sensitive G proteins. The earlier use of lAP as a probe for signal transducers has been reviewed by Ui and his colleagues (Ui, 1984, 1986, 1990; Ui et al., 1984).
