[3H]dynorphin1-8 binding sites in frog (Rana esculenta) brain membranes.
Opioid binding sites specific for [3H]dynorphin1-8 were characterized in the particulate membrane fraction of frog (Rana esculenta) brain. The degradation of the radioligand during the assay was prevented by the use of a broad spectrum of peptidase inhibitors. The binding of [3H]dynorphin1-8 to frog brain membranes was stereoselective, reversible, saturable, and displaceable by a series of opioid ligands including dynorphin1-13, bremazocine, levorphanol and naloxone. The specific binding of [3H]dynorphin1-8 can be significantly inhibited by Na+ ions and/or guanine nucleotides confirming the agonist property of the ligand in vitro. A single set of high affinity opioid binding sites with a Kd approximately 7.5 nM is present in the membranes. The maximum density of binding sites (Bmax approximately 1.1 pmol [3H]dynorphin1-8 per mg protein) was considerably higher than such sites in guinea-pig brain. In addition, comparison with binding of tritiated opioid peptides selective for the mu- and delta-types of opioid receptor showed that in the frog brain most of the sites labelled by [3H]dynorphin1-8 are kappa-sites and that this is a rich source of such sites.
Benyhe
S
S
Institute of Biochemistry, Hungarian Academy of Sciences, Szeged.
Simon
J
J
Borsodi
A
A
Wollemann
M
M
Barnard
E A
EA
D000595:Amino Acid Sequence; D000818:Animals; D001921:Brain / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D004399:Dynorphins / Q000378:metabolism*; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D004743:Enkephalin, Leucine / Q000031:analogs & derivatives / Q000378:metabolism; D004745:Enkephalins / Q000378:metabolism; D016314:Ethylketocyclazocine / Q000378:metabolism; D006165:Guanylyl Imidodiphosphate / Q000378:metabolism; D008969:Molecular Sequence Data; D009270:Naloxone / Q000378:metabolism; D010446:Peptide Fragments / Q000378:metabolism*; D011893:Rana esculenta; D011957:Receptors, Opioid / Q000187:drug effects / Q000378:metabolism*; D012965:Sodium Chloride / Q000494:pharmacology; D014316:Tritium
D004745:Enkephalins; D010446:Peptide Fragments; D011957:Receptors, Opioid; C030738:dynorphin receptor; D014316:Tritium; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D006165:Guanylyl Imidodiphosphate; D009270:Naloxone; D012965:Sodium Chloride; D016314:Ethylketocyclazocine; D004743:Enkephalin, Leucine; D004399:Dynorphins; C034318:enkephalin, Ser(2), Leu(5), Thr(6)-; C026770:dynorphin (1-8)