Many GTP binding proteins demonstrate activity when bound to GTP, and are inactivated via the hydrolysis of the phosphoanhydride bond that links the γ-phosphate to the remainder of the nucleotide, leaving a bound guanosine diphosphate (GDP) and releasing an inorganic phosphate.

This usually occurs rapidly, and the GTP-binding protein can then only be activated by exchanging the GDP for a new GTP molecule.

This prevents the GTP-binding proteins from being inactivated, and allows the cellular processes that they carry out when active to be more easily studied.

[2] The consequences of the constitutive activation of GTP-binding proteins include stimulation of phosphoinositide hydrolysis,[3] cyclic AMP accumulation or elimination,[4] and activation of specific proto-oncogenes.

[5] The 35S labelled radioligand of the compound, 35SGTPγS, is used in autoradiography and G-protein binding studies.