Individual cell types express a characteristic balance between heterotrimeric G protein α and βγ subunits, but little is known about the regulatory mechanism. We systemically examined the regulatory mechanism in CHO cells. We found that expression of Gαs, Gαi2, and Gαq proteins increased in direct proportion to the increase of Gβ1γ2 overexpressed transiently. Expression of Gβ protein also increased following overexpression of Gαs, Gαi2, and Gαq. The Gβγ overexpression stimulated degradation of Gβ in contrast to reduction of Gαs degradation. We conclude that coordinate expression of the G protein subunits involves regulation of protein degradation via proteasome in CHO cells.
