Figure 1.

GAIP interacts with the GTP-bound form of Gα_i3 in vitro. GST-GAIP fusion protein bound to glutathione-agarose beads was incubated with in vitro translated Gα_i3 for 2 hr in the presence or absence of GTP[γS] and AlF₄⁻. The bound products were separated by SDS/10% PAGE and detected by autoradiography. ³⁵S-labeled in vitro translated Gα_i3 binds to GST-GAIP beads 4–5 times more efficiently in the presence of GTP[γS] (lane 2) or AlF₄⁻ (lane 3) than in their absence. Lane 4, control beads with GST alone. Lane 5, ³⁵S-labeled in vitro translated Gα_i3 (arrow). Molecular mass markers (kDa) are indicated on the left.