Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01189 (beta-endorphin)
 21,003 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We studied the binding of [3H]D-Ala2-D-Leu5-enkephalin ([3H]DADLE) and [3H] diprenorphine to crude plasma membrane fraction obtained from the bovine adrenal medulla (bovine adrenal medullary membranes) in order to characterize adrenal medullary opioid receptors. The [3H] diprenorphine binding was the highest in crude plasma membrane-mitochondrial fraction among all subcellular fractions studied. The amount of [3H] diprenorphine bound to bovine adrenal medullary membranes was proportional to the protein concentration. Association kinetics of the [3H] diprenorphine binding to bovine adrenal medullary membranes showed that the maximal binding was achieved following 8 min incubation and that the binding conformed the second-order kinetics. [3H] DADLE and [3H] diprenorphine bound to bovine adrenal medullary membranes with high affinities. The Kd and Bmax for the [3H] DADLE binding were found to be 2.9 nM and 57.5 fmole/mg protein, respectively, while those for the [3H] diprenorphine binding were 0.31 nM and 250 fmole/mg protein, respectively. Displacement studies showed that the [3H] diprenorphine binding was inhibited dose-dependently by levorphanol, dynorphin (1-13), beta-endorphin and DADLE. Levorphanol was at least 1000-fold more potent to inhibit the [3H] diprenorphine binding than dextrorphan, indicating stereospecificity of the [3H] diprenorphine binding. Na+, Li+ and K+ (100 mM) diminished the [3H] DADLE binding and enhanced [3H] diprenorphine binding. Na+ (100 mM) increased the Kd value for the [3H] DADLE binding from 2.9 nM to 14.1 nM. Mn++, Ca++ and Mg++ diminished the [3H] diprenorphine binding. Mn++ (1 mM) increased the Bmax value for the [3H] DADLE binding from 95 fmole/mg protein to 450 fmole/mg protein. These effects of Na+ and Mn++ on the [3H] diprenorphine binding were found to be dose-dependent. [3H] Diprenorphine binding to the digitonin-solubilized opioid receptor was also inhibited dose-dependently by Mn++. These results suggest that bovine adrenal medullary membranes contain high affinity and stereospecific opioid receptors and that the binding of opioids to the bovine adrenal medullary opioid receptors is influenced by cations. Binding study also revealed the presence of opioid receptors in human malignant pheochromocytoma. The Kd and Bmax of the [3H] diprenorphine binding to crude membrane fraction obtained from malignant pheochromocytoma were found to be 0.14 nM and 10.4 fmole/mg protein, respectively.
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PMID:[Characterization of adrenal medullary opioid receptors. I. Binding of opioids to adrenal medullary opioid receptors]. 282 99

Several opioid peptides and narcotic drugs reduced transepithelial potential difference (PD) and short circuit current (Isc) in guinea-pig ileal mucosa measured in vitro in Ussing chambers. [D-Ala2,D-Leu5]enkephalin was the most potent peptide tested. Enkephalin analogues with altered C-terminal amino acids were less potent, as were beta-endorphin and dermorphin. Etorphine produced potent effects whereas morphine and SKF 10,047 were inactive. Ethylketazocine produced a biphasic dose-response curve. When added by themselves diprenorphine and naloxone produced small increases in Isc. This effect was not seen when Cl- and HCO3- in the Ringer were replaced by SO42-. Diprenorphine and naloxone were able to shift the dose response curves for all agonists to the right, with the exception of that for ethylketazocine. Diprenorphine was a more potent antagonist than naloxone. SKF 10,047 also acted as a pure antagonist. Morphine and ethylketazocine had no antagonist effects. It is concluded that the opiate receptor in the guinea-pig ileal mucosa is similar to a delta-opiate receptor as defined by ligand binding studies, but that some differences also exist.
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PMID:Characterization of the opiate receptor in the guinea-pig ileal mucosa. 628 2