Definition:

Guanine nucleotide exchange factors (GEFs) are essential regulators of the spatiotemporal conditions of small GTP-binding protein (SMG) activation. Their cellular activities combine the biochemical stimulation of GDP/GTP exchange, which leads to the active conformation of the SMG, to the detection of upstream signals and, in some cases, interaction with downstream effectors. Inhibition of GEF activities by small molecules has become recently a very active field, both for understanding biology with the tools of chemistry and because GEFs are emerging as therapeutic targets.