GTPdependent

GTPdependent is a term used in biochemistry to denote proteins, enzymes, or cellular processes that require guanosine triphosphate (GTP) to operate. The dependence may be as an energy source, as a cofactor for catalysis, or as a substrate whose hydrolysis drives conformational changes. It is most commonly associated with GTPases and GTP-binding proteins that act as molecular switches in signaling networks and intracellular trafficking.

Mechanistically, many GTP-dependent processes involve cycling between active GTP-bound and inactive GDP-bound states. GTP binding stabilizes an active conformation; hydrolysis to GDP (often with inorganic phosphate release) triggers a conformational change that resets the system. The rate of hydrolysis and the exchange of GDP for GTP, often regulated by guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs), controls timing and specificity.

Prominent examples include translation elongation factors EF-Tu and EF-G, which use GTP to deliver aminoacyl-tRNAs and to power translocation on ribosomes. Small GTPases such as Ras, Rab, and Ran regulate cell signaling, vesicle trafficking, and nuclear transport; dynamin family proteins use GTP hydrolysis to mediate membrane fission. Tubulin’s β-subunit binds GTP and hydrolyzes it during microtubule polymerization, linking GTP states to filament dynamics.

Although the term implies dependence on GTP, some GTP-dependent activities are regulated primarily by GTP binding rather than hydrolysis. GTP-dependent processes are widespread across bacteria, archaea, and eukaryotes and are considered ancient components of cellular energy management and signal transduction.