User:Hebe59/Ras-GRF1

Lead
Ras-GRF1 is a guanine nucleotide exchange factor. Its function is to release guanosine diphosphate, GDP, from the signaling protein RAS, thus increasing the activity of RAS by allowing it to bind to guanosine triphosphate, GTP, returning it to its active state. In this way, Ras-GRF1 has a key role in regulating the RAS signaling pathway. Ras-GRF1 mediates the activation of RAS via Ca2+ bound calmodulin protein.

Article body
Activation of Ras proteins occurs through the phosphorylation of tyrosine receptors. This recruits adapter protein GRB2 which binds to SOS exchange factors, that binds to and activated Ras. Ras/MAPK pathways is activated by the intracellular calcium that binds to the ilimaquinone domain (IQ) on Ras-GRF1. Activated Ras can go on to activate Raf/Mek/Erk which can mediate the activation of CREB transcription factors. This can affect gene expression and cell proliferation.

Ras-GRF1 knockout mice have been shown to have learning and memory deficits associated with dysregulation of this pathway. Ras-GRF1 has also been shown to be upstream from IGF1, allowing it to control growth in mice. Although it is sometimes known as CDC25, it should not be confused with Cdc25. Ras-GRF1 is a paternally expressed imprinted gene, meaning that only the paternal allele of the gene is translated into protein. Disruption of this epigenetic imprinting also produces learning and memory deficits in neonatal mice.