Synembryn-A (RIC8A)

Guanine nucleotide exchange factor (GEF), which can trigger a few, but not all, G-alpha proteins. Able to trigger GNAI1, GNAO1 and GNAQ, but not GNAS by exchanging bound GDP for free GTP.

Involved in regulation of microtubule pulling forces during mitotic motion of chromosomes by stimulating G(I)-alpha protein, potentially leading to release G(I)-alpha-GTP and NuMA proteins in the NuMA-GPSM2-G(I)-alpha-GDP complex (By similarity). Also serves as an activator for G(q)-alpha (GNAQ) protein by boosting the G(q)-coupled receptor-mediated ERK activation.