The effect of C-terminal truncation of the recombinant delta-opioid receptor on Ca2+i signaling.
We have previously shown a stimulatory coupling of the recombinant delta-opioid receptor to phospholipase C leading to production of inositol (1,4,5) triphosphate [Ins(1,4,5)P3] that is affected by truncation of the C-terminus of the receptor. Using a C-terminal mutant of the delta-opioid receptor lacking the final 37 amino acids (CHOdelta37), we examined its coupling to intracellular calcium ion concentration ([Ca2+]i) compared to the full length wild type receptor (CHOdeltaWT) in transfected Chinese hamster ovary (CHO) cells. D-[Pen2,5]enkephalin (DPDPE) mediated increases in [Ca2+]i were measured fluorimetrically in fura-2 loaded whole cell suspensions. DPDPE produced time- and concentration-dependent increases in [Ca2+]i in CHOdeltaWT and CHOdelta37. In both cell types the DPDPE simulated increase in [Ca2+]i was naloxone reversible and pertussis toxin and thapsigargin sensitive. Removal of the C-terminus resulted in a rightward shift of the Ca2+ release concentration-response curve [pEC50 = 8.43 +/- 0.13 and 6.08 +/- 0.25 for CHOdeltaWT and CHOdelta37, respectively]. These data indicate that the C-terminus of the recombinant delta-opioid receptor is important in [Ca2+]i coupling and may be attributed to the effect of C-terminus truncation on phospholipase C coupling reported previously.
Harrison
C
C
University Department of Anaesthesia, Leicester Royal Infirmary, UK.
Rowbotham
D J
DJ
Devi
L A
LA
Lambert
D G
DG
D000595:Amino Acid Sequence / Q000187:drug effects / Q000235:genetics; D000818:Animals; D016466:CHO Cells; D020013:Calcium Signaling / Q000187:drug effects / Q000235:genetics*; D003001:Cloning, Molecular; D006224:Cricetinae; D004174:Diprenorphine / Q000493:pharmacokinetics; D020881:Enkephalin, D-Penicillamine (2,5)- / Q000494:pharmacology; D051379:Mice; D009292:Narcotic Antagonists / Q000493:pharmacokinetics; D017465:Receptors, Opioid, delta / Q000819:agonists / Q000235:genetics*
D009292:Narcotic Antagonists; D017465:Receptors, Opioid, delta; D004174:Diprenorphine; D020881:Enkephalin, D-Penicillamine (2,5)-