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 Snyder, 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 Gα subunit. The addition of the G-protein activator AlF4- modulated the 125I-CTX binding characteristics of the solubilized CTXR. Further immunological analyses employing Gα subunit-specific antibodies to monitor the cofractionation of Gα with 125I-CTX binding activity throughout the purification procedure indicate the selective recovery of Goα in the purified CTXR preparation, as neither Gsα, Giα, nor Gβγ could be detected. Furthermore, Goα associated with CTXR acted as a substrate for pertussis toxin-dependent ADP-ribosylation only upon the addition of exogenous Gβγ subunits. These results strongly indicate a high affinity complex between an activated Goα and CTXR maintained throughout biochemical purification of the 125I-CTX receptor.
|Original language||English (US)|
|Number of pages||4|
|Journal||Journal of Biological Chemistry|
|State||Published - Jan 7 1994|
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology