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Evidence for a 95 kDa Short Form of the α1A Subunit Associated with the ω-Conotoxin MVIIC Receptor of the P/Q-type Ca2+ Channels
Journal article   Open access   Peer reviewed

Evidence for a 95 kDa Short Form of the α1A Subunit Associated with the ω-Conotoxin MVIIC Receptor of the P/Q-type Ca2+ Channels

Victoria E. S Scott, Ricardo Felix, Jyothi Arikkath and Kevin P Campbell
The Journal of neuroscience, Vol.18(2), pp.641-647
01/15/1998
DOI: 10.1523/JNEUROSCI.18-02-00641.1998
PMID: 9425006
url
https://doi.org/10.1523/JNEUROSCI.18-02-00641.1998View
Published (Version of record) Open Access

Abstract

Neuronal voltage-dependent Ca 2+ channels have been isolated previously and shown to contain a primary α 1 pore-forming subunit as well as auxiliary α 2 δ and β subunits, in addition to an uncharacterized 95 kDa protein. In the present study, using multiple approaches, we have extensively characterized the molecular structure of the 95 kDa protein. Separation of the P/Q- and N-type neuronal Ca 2+ channels showed that the 95 kDa protein is associated exclusively with the ω-Conotoxin MVIIC receptor of the P/Q-type channels. Analysis of purified synaptic plasma membranes and the isolated P/Q-type channels, using α 1A -specific antibodies, suggested a structural relationship between the α 1A subunit and the 95 kDa protein. This finding was supported by protein–protein interaction data, which revealed that the β subunit can associate with the 95 kDa protein in addition to the α 1A subunit. Changes in electrophoretic mobility after enzymatic treatment with Endo F indicated that the 95 kDa protein is glycosylated. Furthermore, microsequencing of the 95 kDa protein yielded 13 peptide sequences, all of which are present in the first half of the α 1A subunit up to amino acid 829 of the cytoplasmic linker between repeats II and III. Taken together, our results strongly suggest that the 95 kDa glycoprotein associated with the P/Q-type Ca 2+ channels is a short form of the α 1A subunit.
 P N-type Ca2+channel β subunit ω-Conotoxin GVIA ω-Conotoxin MVIIC 95 kDa subunit Q-type Ca2+ channels α1A subunit

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