Guanosine triphosphate phosphohydrolases, also known as GTPases, are a class of enzymes that facilitate the hydrolysis of guanosine triphosphate (GTP) into guanosine diphosphate (GDP) by breaking the phosphoanhydride bond between the gamma and beta phosphate groups of GTP. This hydrolysis reaction is accompanied by the release of inorganic phosphate (Pi).
GTPases play a crucial role in cellular processes such as signal transduction, protein synthesis, cell division, vesicle trafficking, and cytoskeletal rearrangement. They function as molecular switches, cycling between an active GTP-bound state and an inactive GDP-bound state. The activation and deactivation of GTPases are regulated by various factors, including guanine nucleotide exchange factors (GEFs) that promote GTP binding and GTPase-activating proteins (GAPs) that enhance GTP hydrolysis.
The hydrolytic activity of GTPases is essential for regulating their biological functions and enables them to control the timing and duration of cellular processes. Dysregulation or mutations in GTPase activity can lead to the disruption of cellular signaling pathways, contributing to the development of various diseases, including cancer.
GTPases are classified into several families, including the Ras superfamily, which includes Ras, Rho, Rab, Arf, and Ran proteins, as well as the heterotrimeric GTP-binding proteins (G proteins) involved in cellular signal transduction. Each GTPase family has its own distinct functions and regulatory mechanisms, but they all share the common feature of utilizing GTP hydrolysis as a means to regulate cellular processes.
