binding of thyrotropin-releasing hormone ( trh , thyroliberin ) to receptors in chilled membrane resuspensions from sheep anterior pituitary glands is reduced in affinity almost 2-fold by micromolar concentrations of guanosine 5'-triphosphate ( gtp ) and the hydrolysis-resistant analog guanyl-5'-yl imidodiphosphate ( gppnhp ) added to tissue during a 10-min preincubation at 37 degree c .
C0018353
guanosine
C0018366
guanyl-5