GTP functions as a carrier of phosphates and pyrophosphates involved in channeling chemical energy into specific biosynthetic pathways. GTP activates the signal transducing G proteins which are involved in various cellular processes including proliferation, differentiation, and activation of several intracellular kinase cascades. Proliferation and apoptosis are regulated in part by the hydrolysis of GTP by small GTPases Ras and Rho. Another type of small GTPase, Rab, plays a role in the docking and fusion of vesicles and may also be involved in vesicle formation. In addition to its role in signal transduction, GTP also serves as an energy-rich precursor of mononucleotide units in the enzymatic biosynthesis of DNA and RNA.
