Guanylate-binding protein (GBP), C-terminal domain. Guanylate-binding proteins (GBPs) are synthesized after activation of the cell by interferons. The biochemical properties of GBPs are clearly different from those of Ras-like and heterotrimeric GTP-binding proteins. They bind guanine nucleotides with low affinity (micromolar range), are stable in their absence, and have a high turnover GTPase. In addition to binding GDP/GTP, they have the unique ability to bind GMP with equal affinity and hydrolyze GTP not only to GDP, but also to GMP. This C-terminal domain has been shown to mediate inhibition of endothelial cell proliferation by inflammatory cytokines.