K. Schulz et al., RAT BETA-ADRENERGIC-RECEPTOR KINASE-1 AND KINASE-2 IN MOUSE NEUROBLASTOMA X RAT GLIOMA NG 108-15 HYBRID-CELLS, Biochemical pharmacology, 55(1), 1998, pp. 65-70
Beta-adrenergic receptor kinase (beta ARK, EC 2.7.1.-) has been implic
ated 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, thi
s investigation was designed to find out whether NG 108-15 cells conta
in 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 presen
ce of mouse beta ARK. Examining the cytosolic beta ARK activity in the
se hybrid cells using rhodopsin as substrate, we found a strict functi
onal 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 man
ner. The results reported here provide the basis to study more closely
the molecular function of G protein-coupled receptor kinases in a cel
l line (NG 108-15) most frequently used to investigate acute and chron
ic opioid actions. (C) 1998 Elsevier Science Inc.