Ability of delta-opioid receptors to interact with multiple G-proteins is independent of receptor density

To determine whether the previously demonstrated ability of delta-opioid receptors to interact simultaneously with multiple G-proteins was a function of high receptor levels, this interaction was investigated in Chinese hamster ovary cells stably expressing 10 different levels of cloned delta-opioid...

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Bibliographic Details
Published in:The Journal of biological chemistry 1994-08, Vol.269 (33), p.21293-21302
Main Authors: PRATHER, P. L, MCGINN, T. M, ERICKSON, L. J, EVANS, C. J, LOH, H. H, PING-YEE LAW
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Animals
Biological and medical sciences
Cell physiology
Cell receptors
Cell structures and functions
CHO Cells
Cloning, Molecular
Cricetinae
Cricetulus
Enkephalin, Leucine-2-Alanine - pharmacology
Fundamental and applied biological sciences. Psychology
GTP-Binding Proteins - metabolism
Molecular and cellular biology
Molecular Sequence Data
Naloxone - pharmacology
Neuropeptide receptors
Receptors, Opioid, delta - drug effects
Receptors, Opioid, delta - genetics
Receptors, Opioid, delta - metabolism
Signal transduction
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Summary:To determine whether the previously demonstrated ability of delta-opioid receptors to interact simultaneously with multiple G-proteins was a function of high receptor levels, this interaction was investigated in Chinese hamster ovary cells stably expressing 10 different levels of cloned delta-opioid receptors, ranging from 18,000 to 1.6 x 10(6) receptors/cell. The opioid agonist D-Ala2,D-Leu5-enkephalin (DADLE) inhibited forskolin-stimulated adenylyl cyclase activity in all 10 clones with variable maximal inhibitory levels. Furthermore, opioid agonists altered incorporation of [alpha-32P]azidoanilido-GTP into at least four G-protein alpha-subunits in all 10 clones, three of which were determined to be Gi3 alpha, Gi2 alpha and Go2 alpha. This effect was concentration-dependent, naloxone-reversible, and delta-opioid agonist-specific and was blocked by pretreatment with pertussis toxin. Although DADLE induced an increase in the incorporation of [alpha-32P]azidoanilido-GTP into three of the four G alpha proteins that was independent of receptor density, the magnitude of this response was greater as receptor density increased. In addition, concentrations of DADLE required to promote 50% maximal labeling were similar for all four G alpha proteins within each clone and did not appear to be affected by receptor density. Therefore, the ability of delta-opioid receptors to interact with multiple G-proteins is independent of receptor density and there is also no apparent correlation between the amount of G-protein activated and the maximal effect of an agonist.
ISSN:0021-9258
1083-351X
DOI:10.1016/S0021-9258(17)31962-2