Human beta-endorphin: specific binding in neuroblastoma N18TG2 cells.

The mouse neuroblastoma N18TG2 has specific, saturable binding sites for human beta-endorphin (beta h-EP). The affinity and number of sites are 1.1 nM and 280,000 per cell, respectively, beta h-EP binding is not inhibited by [Leu]enkephalin or morphine at concentrations up to 0.1 mM; beta h-EP-(6--31) is a potent inhibitor of binding, and camel beta-EP is much less potent. The data suggest the importance of the nonenkephalin segment of the beta h-EP molecule for interaction with the binding site in N18TG2 cells.