as early as postnatal day 1 , gabab receptors are present and are linked to both calcium- and guanosine triphosphate-binding protein ( g protein ) -regulatory sites , as indicated by the stimulation of binding by calcium and the inhibition of binding by the guanine nucleotide guanosine 5'-o- ( 3-thiotriphosphate ) ( gtp gamma s ) .
C0018353
guanosine triphosphate
C0079469
gtp gamma s