G protein β1γ2 subunits purification and their interaction with adenylyl cyclase

A preliminary study on the interaction of G protein (guanine triphosphate binding protein) beta(1)gamma(2) subunits and their coupled components in cell signal transduction was conducted in vitro. The insect cell lines, Sf9 (Spodoptera frugiperda) and H5 (Trichoplusia ni) were used to express the recombinant protein Gbeta(1)gamma(2). The cell membrane containing Gbeta(1)gamma(2) was isolated through affinity chromatography column with Ni-NTAagarose by FPLC method, and the highly purified protein was obtained. The adenylyl cyclase 2 (AC(2)) activity assay showed that the purified Gbeta(1)gamma(2) could significantly stimulate AC(2) activity. The interaction of beta(1)gamma(2) subunits of G protein with the cytoplasmic tail of various mammalian adenylyl cyclases was monitored by BIAcore technology using NTA sensor chip, which relies on the phenomenon of surface plasmon resonance (SPR). The experiments showed the direct binding of Gbeta(1)gamma(2) to the cytoplasmic tail C2 domain of AC2. The specific binding domain of AC2 with Gbeta(1)gamma(2) was the same as AC2 activity domain which was stimulated by Gbeta(1)gamma(2).