TY - JOUR
T1 - Coupling of exogenous receptors to phospholipase C in Xenopus oocytes through pertussis toxin-sensitive and -insensitive pathways. Cross-talk through heterotrimeric G-proteins
AU - Moriarty, T. M.
AU - Sealfon, S. C.
AU - Carty, D. J.
AU - Roberts, J. L.
AU - Iyengar, R.
AU - Landau, E. M.
PY - 1989
Y1 - 1989
N2 - Heterotrimeric guanine nucleotide-binding proteins (G-proteins) can be categorized into molecularly divergent groups by their differential sensitivity to pertussis toxin. Receptors specifically use either pertussis toxin-sensitive or -insensitive G-proteins to couple to specific effectors. Receptor stimulation of phospholipase C, however, is pertussis toxin sensitive in some systems and pertussis toxin insensitive in others. We studied the coupling of receptors to phospholipase C by expressing receptors from both systems into a single cell, the Xenopus oocyte. [Arg8]Vasopressin (AVP) receptors from liver and cholecystokinin-8 (sulfated) (CCK) receptors from brain were expressed in oocytes by intracellular injection of RNA. Both receptors stimulated a Ca2+-dependent Cl- current which can also be evoked by intracellular injection of inositol 1,4,5-trisphosphate. Hence, receptor stimulation of phospholipase C was measured as the evoked Ca2+-dependent Cl- current. The liver AVP receptor, which is known to stimulate phospholipase C in a pertussis toxin-insensitive manner (Lynch, C.J., Prpic, V., Blackmore, P.F., and Exton, J.H. (1986) Mol. Pharmacol. 29, 196-203), was found to stimulate phospholipase C through a pertussis toxin-sensitive pathway in the Xenopus oocyte. The CCK receptor from brain stimulated phospholipase C through a pertussis toxin-insensitive pathway. Both AVP and CCK stimulation of phospholipase C were attenuated by the intracellular injection of excess G-protein βγ subunits. Neither pertussis toxin treatment nor intracellular injection of βγ subunits affected any steps subsequent to inositol 1,4,5-trisphosphate production. From these data we conclude that both the pertussis toxin-sensitive and -insensitive pathways for receptor coupling to phospholipase C are transduced by heterotrimeric G-proteins. We also find that there is a lack of coupling fidelity of receptors to G-protein in stimulation of phospholipase C which can be influenced by the membrane environment.
AB - Heterotrimeric guanine nucleotide-binding proteins (G-proteins) can be categorized into molecularly divergent groups by their differential sensitivity to pertussis toxin. Receptors specifically use either pertussis toxin-sensitive or -insensitive G-proteins to couple to specific effectors. Receptor stimulation of phospholipase C, however, is pertussis toxin sensitive in some systems and pertussis toxin insensitive in others. We studied the coupling of receptors to phospholipase C by expressing receptors from both systems into a single cell, the Xenopus oocyte. [Arg8]Vasopressin (AVP) receptors from liver and cholecystokinin-8 (sulfated) (CCK) receptors from brain were expressed in oocytes by intracellular injection of RNA. Both receptors stimulated a Ca2+-dependent Cl- current which can also be evoked by intracellular injection of inositol 1,4,5-trisphosphate. Hence, receptor stimulation of phospholipase C was measured as the evoked Ca2+-dependent Cl- current. The liver AVP receptor, which is known to stimulate phospholipase C in a pertussis toxin-insensitive manner (Lynch, C.J., Prpic, V., Blackmore, P.F., and Exton, J.H. (1986) Mol. Pharmacol. 29, 196-203), was found to stimulate phospholipase C through a pertussis toxin-sensitive pathway in the Xenopus oocyte. The CCK receptor from brain stimulated phospholipase C through a pertussis toxin-insensitive pathway. Both AVP and CCK stimulation of phospholipase C were attenuated by the intracellular injection of excess G-protein βγ subunits. Neither pertussis toxin treatment nor intracellular injection of βγ subunits affected any steps subsequent to inositol 1,4,5-trisphosphate production. From these data we conclude that both the pertussis toxin-sensitive and -insensitive pathways for receptor coupling to phospholipase C are transduced by heterotrimeric G-proteins. We also find that there is a lack of coupling fidelity of receptors to G-protein in stimulation of phospholipase C which can be influenced by the membrane environment.
UR - http://www.scopus.com/inward/record.url?scp=0024308386&partnerID=8YFLogxK
M3 - Article
C2 - 2474532
AN - SCOPUS:0024308386
SN - 0021-9258
VL - 264
SP - 13524
EP - 13530
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 23
ER -