Preparation of functional human lysophosphatidic acid receptor 2 using a P9∗ expression system and an amphipathic polymer and investigation of its in vitro binding preference to Gα proteins

Human lysophosphatidic acid receptor 2 (LPA2), a member of the G-protein coupled receptor family, mediates lysophosphatidic acid (LPA)-dependent signaling by recruiting various G proteins. Particularly, it is directly implicated in the progression of colorectal and ovarian cancer through G protein signaling cascades. To investigate the biochemical binding properties of LPA2 against various alpha subunits of G protein (Gα), a functional recombinant LPA2 was overexpressed in E. coli membrane with a P9∗ expression system, and the purified protein was stabilized with an amphipathic polymer that had been synthesized by coupling octylamine, glucosamine, and diethyl aminoproylamine at the carboxylic groups of poly-γ-glutamic acid. The purified LPA2 stabilized with the amphipathic polymer showed selective binding activity to the various Gα proteins as well as agonist-dependent dissociation from Gαi3. Understanding the binding properties of LPA2 against various Gα proteins advances the understanding of downstream signaling cascades of LPA2. The functional LPA2 prepared using a P9∗ expression system and an amphipathic polymer could also facilitate the development of LPA2-targeting drugs.