beta-Endorphin: characteristics of binding sites in a neuroblastoma--glioma hybrid cell

Proc Natl Acad Sci U S A. 1981 Apr;78(4):2218-20. doi: 10.1073/pnas.78.4.2218.


Specific binding of human beta-endorphin to NG108-15 cells is described; human beta-[Tyr27-3H2] endorphin was used as the ligand. The binding is time dependent and saturable; Kd = 0.3 nM and ka = 1.8 x 10(8) M-1 min-1. Under the conditions optimal for beta-endorphin binding, leucine-enkephalin has one-fourth to one-third as many binding sites as beta-endorphin and its affinity is 7--10% that of beta-endorphin. Monovalent and divalent cations potently inhibit binding. Trypsin, phospholipase A, and N-ethylmaleimide reduce the ability of NG108-15 cells to bind beta-endorphin. beta-Endorphin analogs are able to fully inhibit the binding of beta-[Tyr27-3H2]endorphin, although enkephalins, morphine, and naloxone inhibit only 50--80%.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Cell Line
  • Endorphins / metabolism*
  • Enkephalins / metabolism
  • Glioma / metabolism*
  • Kinetics
  • Ligands
  • Neoplasms, Experimental / metabolism
  • Neuroblastoma / metabolism*
  • Phospholipids / metabolism
  • Rats
  • Receptors, Opioid / metabolism*
  • Structure-Activity Relationship


  • Endorphins
  • Enkephalins
  • Ligands
  • Phospholipids
  • Receptors, Opioid