employing the mu-selective opioid agonist [ d-ala2 , mephe4 , gly-ol5 ] enkephalin ( damgo ) in direct binding studies and in competition of labeled antagonist binding , we found that the major changes were a decrease in the number of sites with high affinity for agonist , a small reduction in total receptor number , and a loss in the ability of guanosine 5'- [ gamma-thio ] triphosphate to regulate binding .
C0014298
enkephalin
C0525773
damgo