Chaperone that specifically binds and folds nascent G alpha proteins prior to G protein heterotrimer formation, promoting their stability and activity: folds GNAI1, GNAO1, GNA13 and GNAQ. Does not fold G(s) G-alpha proteins GNAS nor GNAL. Also acts as a guanine nucleotide exchange factor (GEF) for G alpha proteins by stimulating exchange of bound GDP for free GTP. Involved in regulation of microtubule pulling forces during mitotic movement of chromosomes by stimulating G(i)-alpha protein (GNAI1), possibly leading to release G(i)-alpha-GTP and NuMA proteins from the NuMA-GPSM2-G(i)-alpha-GDP complex. Also acts as an activator for G(q)-alpha (GNAQ) protein by enhancing the G(q)-coupled receptor-mediated ERK activation 