Rat beta-adrenergic receptor kinases 1 and 2 in mouse neuroblastoma X rat glioma NG 108-15 hybrid cells

Beta-adrenergic receptor kinase (beta ARK, EC 2.7.1.-) has been implicated in the phosphorylation of G protein-coupled receptors, including opioid receptors. Since delta-opioid receptors of mouse neuroblastoma X rat glioma hybrid cells (NG 108-15) desensitize upon activation, this investigation was designed to find out whether NG 108-15 cells contain beta ARK activity. Using the reverse transcription polymerase chain reaction technique, we identified two mRNAs, one coding for rat beta ARK1 and the other for rat beta ARK2. No hint was found for the presence of mouse beta ARK. Examining the cytosolic beta ARK activity in these hybrid cells using rhodopsin as substrate, we found a strict functional dependence on the presence of exogenous G protein subunit G beta gamma. This relationship reflects a characteristic for beta ARK1 and 2 out of the known G protein-coupled receptor kinases. Finally, highly purified recombinant beta ARK1 proved active to phosphorylate enriched delta-opioid receptor preparations in an opioid agonist-dependent manner. The results reported here provide the basis to study more closely the molecular function of G protein-coupled receptor kinases in a cell line (NG 108-15) most frequently used to investigate acute and chronic opioid actions. (C) 1998 Elsevier Science Inc.