Energy transfer GTP is involved in energy transfer within the cell. For instance, a GTP molecule is generated by one of the enzymes in the
citric acid cycle. This is tantamount to the generation of one molecule of
ATP, since GTP is readily converted to ATP with
nucleoside-diphosphate kinase (NDK).
Genetic translation During the elongation stage of
translation, GTP is used as an energy source for the binding of a new amino-bound
tRNA to the A site of the
ribosome. GTP is also used as an energy source for the translocation of the ribosome towards the 3' end of the
mRNA.
Microtubule dynamic instability During
microtubule polymerization, each heterodimer formed by an alpha and a beta
tubulin molecule carries two GTP molecules, and the GTP is hydrolyzed to GDP when the tubulin dimers are added to the plus end of the growing microtubule. Such GTP hydrolysis is not mandatory for microtubule formation, but it appears that only GDP-bound tubulin molecules are able to depolymerize. Thus, a GTP-bound tubulin serves as a cap at the tip of a microtubule to protect it from depolymerization; and, once the GTP is hydrolyzed, the microtubule begins to depolymerize and shrink rapidly.
Mitochondrial function The translocation of proteins into the
mitochondrial matrix involves the interactions of both GTP and ATP. The importing of these proteins plays an important role in several pathways regulated within mitochondria, such as converting
oxaloacetate to
phosphoenolpyruvate (PEP) in gluconeogenesis. ==Precursor for synthesis of riboflavin==