GTPgammaS is nonhydrolyzable (although in some cases such as with dynamin it is slowly hydrolyzable) G-protein-activating analog of guanosine triphosphate

Guanosine triphosphate

Guanosine-5'-triphosphate is a purine nucleoside triphosphate. It can act as a substrate for the synthesis of RNA during the transcription process...

 (GTP). It has many physiological actions such as stimulation of guanine nucleotide-binding proteins, phosphoinositide hydrolysis

Hydrolysis

Hydrolysis is a chemical reaction during which molecules of water are split into hydrogen cations and hydroxide anions in the process of a chemical mechanism. It is the type of reaction that is used to break down certain polymers, especially those made by condensation polymerization...

, cyclic AMP accumulation, and activation of specific proto-oncogenes. Its 35GS labelled radioligand [³⁵S]GTPgammaS is used in autoradiography and G-protein binding studies.