Figure 4.

In vitro interactions of AGS3 with Gα_i3 assessed by surface plasmon resonance. AGS3 interacts with Gα_i3-GDP but not with Gα_i3-GTPγS or Gα_i3-GDP-AlF₄⁻. GST-AGS3_424–650 fusion protein or GST protein were bound to anti-GST IgG covalently coupled to separate Biacore chips. Gα_i3 was preincubated with GDP, AlF₄⁻, or GTPγS as described in Materials and Methods and then injected in the flow buffer (simultaneous coinjection over both chips) into a BIAcore 2000. The signal generated by GST alone was deducted from the GST-AGS3_424–650 signal.