Figure 1.

Regulation of small GTPases. Small GTPases (small G proteins) act as molecular switches to regulate downstream effectors which can exist either in GDP or GTP-bound state. To perform their regulatory function, small GTPases cycle between GDP-bound inactive states and GTP-bound active states. Guanine Nucleotide Exchange Factor (GEF) converts small GTPase to GTP-bound form. GTPase-activating protein (GAP) promotes GTPase activity of small G proteins facilitating its return to GDP-bound form.