Used as a non-hydrolyzable analog of GTP in biochemical studies to stabilize G-protein conformations, enabling researchers to investigate G-protein coupled receptor (GPCR) signaling pathways without degradation by GTPases. Commonly applied in nucleotide-binding assays, structural studies, and enzyme kinetics to lock G-proteins in their active state. Also utilized in cryo-EM and X-ray crystallography to capture transient active states of G-proteins and related complexes.