The association of endogenous G(oα) with the purified ω-conotoxin GVIA receptor

M. W. McEnery, A. M. Snowman, S. H. Snyder

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Abstract

Modulation of the neuronal ω-conotoxin GVIA-sensitive N-type voltage- dependent calcium channel (VDCC) by neurotransmitters and guanine nucleotides suggests a dynamic interaction between activated G-protein α subunits and the N-type VDCC. Our previous report on the purification of the N-type VDCC (McEnery, M. W., Snowman, A. M., Sharp, A. H., Adams, M. E., and Synder, S. H. (1991) Proc. Natl. Acad. Sci. U. S. A. 88, 11095-11099), has led us to investigate a possible association of CTXR with an endogenous G(α) subunit. The addition of the G-protein activator AlF4/- modulated the 125I-CTX binding characteristics of the solubilized CTXR. Further immunological analyses employing G(α) subunit-specific antibodies to monitor the cofractionation of G(α) with 125I-CTX binding activity throughout the purification procedure indicate the selective recovery of G(oα) in the purified CTXR preparation, as neither G(sα), G(iα), nor G(βγ) could be detected. Furthermore, G(oα) associated with CTXR acted as a substrate for pertussis toxin-dependent ADP-ribosylation only upon the addition of exogenous G(βγ) subunits. These results strongly indicate a high affinity complex between an activated G(oα) and CTXR maintained throughout biochemical purification of the 125I-CTX receptor.

Original languageEnglish (US)
Pages (from-to)5-8
Number of pages4
JournalJournal of Biological Chemistry
Volume269
Issue number1
StatePublished - 1994

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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