Identification of the G-protein alpha-subunit encoded by alpha o2 cDNA as a 39 kDa pertussis toxin substrate

A novel form of the Go alpha-subunit (alpha o2) has been identified by molecular cloning (Hsu et al., J. Biol. Chem. 265, 11220-11226, 1990). An antibody was generated against a synthetic peptide corresponding to a region of the protein encoded by alpha o2 cDNA. The antibody reacted with an apparently single 39 kDa protein in membrane preparations of rodent brain and with a 39 kDa pertussis toxin substrate in membranes of rodent neuroendocrine and pituitary cells. A previously produced antibody raised against a region common to proteins encoded by alpha o2 cDNA and the previous cloned alpha o1 cDNA (Itoh et al., Proc. Natl. Acad. Sci. USA 83, 3776-3780, 1986) recognized proteins of 39 and 40 kDa in preparations of bovine, porcine and rodent brain and pertussis toxin substrates of 39 and 40 kDa in membranes of rodent neuroendocrine and pituitary cells. We conclude that the 39 kDa Go alpha subunit is encoded by alpha o2 cDNA.