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A Calcium Channel from the Presynaptic Nerve Terminal of the Narke japonica Electric Organ Contains a Non‐N‐Type α 2 δ Subunit
Author(s) -
Tokumaru Hiroshi,
Shojaku Suzuyo,
Takehara Hiroaki,
Hirashima Naohide,
Abe Teruo,
Saisu Hideo,
Kirino Yutaka
Publication year - 1995
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.1995.65020831.x
Subject(s) - n type calcium channel , r type calcium channel , protein subunit , calcium channel , synaptosome , calcium , chemistry , voltage dependent calcium channel , biochemistry , affinity chromatography , sepharose , l type calcium channel , biophysics , microbiology and biotechnology , biology , membrane , t type calcium channel , organic chemistry , gene , enzyme
A monoclonal antibody (MCC‐1) that recognizes the α 2 δ subunit complex of L‐type calcium channels from rabbit skeletal muscle membranes partially inhibited the evoked release of acetylcholine from synaptosomes isolated from the electric organ of the marine electric ray, Narke japonica . Digitonin extracts of synaptosomal plasma membranes were subjected to immunoaffinity column chromatography on MCC‐1‐Sepharose. The purified fraction contained a 170‐kDa protein that reacts with MCC‐1 and dissociates into smaller polypeptides under reducing conditions. In addition, immunoblotting analysis revealed the existence of syntaxin in the purified fraction, suggesting that the calcium channel forms a complex with syntaxin. However, MCC‐1 did not immunoprecipitate an ω‐conotoxin GVIA‐binding protein. These findings indicate that the 170‐kDa protein may be the α 2 δ subunit of a calcium channel that is distinct from the ω‐conotoxin GVIA‐sensitive N‐type calcium channel and partially responsible for the calcium influx that triggers the evoked release of acetylcholine.