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Description

Synembryn-A (UniProt: Q80ZG1, also known as Resistance to inhibitors of cholinesterase 8, Protein Ric-8A) is encoded by the Ric8a gene (Gene ID: 293614) in rat species. Resistance to inhibitors of cholinesterase 8 (RIC-8) is conserved in vertebrates and is concentrated in the cytoplasm of neurons. Mammalian Ric-8 proteins are G alpha subunit guanine nucleotide exchange factors. Ric-8A and Ric-8B collectively stimulate nucleotide exchange of all G alpha subunit classes by stabilizing the G alpha nucleotide-free transition state. Ric-8 is reported to directly participate in the post-translational folding of nascent G alpha subunits to promote G-protein biosynthesis. It may facilitate the transition of G alpha from a pre-folded globular state to its native state by promoting the first G alpha guanine nucleotide-binding event. Ric-8 interacts with GDP-bound G alpha proteins, but does not interact with G-alpha proteins when they are in complex with beta and gamma subunits. Overexpression of Ric-8 proteins in HEK293, NIH 3T3, or Sf9 cells is shown to enhance cellular G alpha levels. Embryonic stem cells lacking Ric-8A or Ric-8B produce defective G alpha subunits that turn over at about 10-fold higher rates than in wild-type cells. Ref.: Thomas, C.J. et al. (2011). PLoS ONE 6(8): e23197.