The association of endogenous Go alpha with the purified omega-conotoxin GVIA receptor.
Modulation of the neuronal omega-conotoxin GVIA-sensitive N-type voltage-dependent calcium channel (VDCC) by neurotransmitters and guanine nucleotides suggests a dynamic interaction between activated G-protein alpha 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 G alpha subunit. The addition of the G-protein activator AIF4- modulated the 125I-CTX binding characteristics of the solubilized CTXR. Further immunological analyses employing G alpha subunit-specific antibodies to monitor the cofractionation of G alpha with 125I-CTX binding activity throughout the purification procedure indicate the selective recovery of Go alpha in the purified CTXR preparation, as neither Gs alpha, Gi alpha, nor G beta gamma could be detected. Furthermore, Go alpha associated with CTXR acted as a substrate for pertussis toxin-dependent ADP-ribosylation only upon the addition of exogenous G beta gamma subunits. These results strongly indicate a high affinity complex between an activated Go alpha and CTXR maintained throughout biochemical purification of the 125I-CTX receptor.
McEnery
M W
MW
Department of Physiology and Biophysics, Case Western Reserve School of Medicine, Cleveland, Ohio 44106.
Snowman
A M
AM
Snyder
S H
SH
D000818:Animals; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism*; D008978:Mollusk Venoms / Q000378:metabolism*; D010455:Peptides / Q000378:metabolism* / Q000633:toxicity; D051381:Rats; D020866:omega-Conotoxin GVIA
D015220:Calcium Channels; D008978:Mollusk Venoms; D010455:Peptides; C053157:omega-conotoxin receptor; D020866:omega-Conotoxin GVIA; D019204:GTP-Binding Proteins