Leucine-2-alanine enkephalin induced delta opioid receptors internalization expressed stably in CHO cells.
OBJECTIVE
To characterize the internalization of delta opioid receptors (DOR) stably expressed in Chinese hamster ovary (CHO) cells and the role of the C-terminal in this process.


METHODS
Receptor membrane anchoring was shown by immunofluorescence microscopy. Receptor internalization was assessed by measuring the radioligand binding resistant to the acid-buffer wash.


RESULTS
Originally, all the wild-type (CHO-W) and C-truncated (CHO-T) DOR expressed were localized to the membrane. Agonist [3H] leucine-2-alanine enkephalin (LAE) but not the antagonist [3H]diprenorphine (Dip) induced rapid receptor internalization. The internalization of C-truncated DOR in CHO-T was similar to that of the wild-type in maximal level, but climbed up more slowly. DOR internalization was extracellular osmolarity- and temperature-sensitive. Pertussis toxin and universal protein kinase inhibitor staurosporine had no effect on it.


CONCLUSIONS
DOR internalization is an agonist and clathrin-coated pits dependent, but post-receptor cellular signal transduction independent process; moreover, the C-terminal of DOR, not engaged in membrane anchoring, affects the initialization of DOR internalization.
Wang
C H
CH
Shanghai Institute of Materia Medica, Chinese Academy of Sciences, China.
Zhou
D H
DH
Chen
J
J
Chi
Z Q
ZQ
D000818:Animals; D016466:CHO Cells / Q000378:metabolism; D006224:Cricetinae; D004174:Diprenorphine / Q000494:pharmacology; D016308:Enkephalin, Leucine-2-Alanine / Q000494:pharmacology*; D010957:Plasmids; D017465:Receptors, Opioid, delta / Q000235:genetics / Q000378:metabolism*; D014162:Transfection
D017465:Receptors, Opioid, delta; D004174:Diprenorphine; D016308:Enkephalin, Leucine-2-Alanine