in contrast to the binding of the mu-selective opioid agonist , [ 3h ] [ d-ala2 , mephe4 , glyol5 ] enkephalin , and the delta-selective opioid agonist , [ 3h ] [ d-penicillamine2 , d-penicillamine5 ] enkephalin , [ 125i ] beta h-endorphin binding was not affected by gtp or guanylyl-5'-imidodiphosphate in a concentration-dependent manner in the absence of cations .
C0018353
gtp
C0018366
guanylyl