Synthesis and applications of affinity matrix containing immobilized βγ subunits of G proteins

This chapter discusses synthesis and applications of affinity matrix containing immobilized βγ subunits of G proteins. All G proteins composed of α,β, and γ subunits. Stimulation of the proteins is effected by exchange of GTP for GDP. This activation can be mimicked, in vitro, by the binding of AIF₄^- in concert with guanosine 5'-diphosphate (GDP). Activation promotes dissociation of α and βγ subunits. Because generic purified complexes of βγ subunits interact with a wide variety of unique α subunits, it is possible to use βγ as an affinity reagent for the study of α subunits. The development of a functional immobilized βγ resin provided a novel method for isolating and purifying α subunits of G proteins and a unique means for studying the interaction between α and βγ subunits. The immobilization of βγ subunits on ω-aminobutyl-agarose takes advantage of the relative insensitivity of the function of βγ subunits to modification by maleimides.