Purification and functional analysis of Ric-8A: A guanine nucleotide exchange factor for G-protein α subunits

Abstract Ric-8A (synembryn) has been shown to accelerate the in vitro guanine nucleotide exchange activities of most G-protein α subunits (with the exception of Gα s ). Methods are presented in this article for the purification of Ric-8A and functional analysis of the effects Ric-8A has on G-protein α subunit guanine nucleotide-binding activities. The use of Ric-8A to prepare GTPγS-Gα and nucleotide-free Gα (in complex with Ric-8A) is described.