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The α2/δ subunit of voltage sensitive Ca 2+ channels is a single transmembrane extracellular protein which is involved in regulated secretion
Author(s) -
Wiser Ofer,
Trus Michael,
Tobi Dror,
Halevi Sarah,
Giladi Eli,
Atlas Daphne
Publication year - 1996
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(95)01475-6
Subject(s) - protein subunit , g alpha subunit , interleukin 10 receptor, alpha subunit , extracellular , interleukin 5 receptor alpha subunit , scn3a , biology , microbiology and biotechnology , xenopus , alpha (finance) , gamma subunit , transmembrane domain , transmembrane protein , membrane potential , western blot , gi alpha subunit , gamma aminobutyric acid receptor subunit alpha 1 , biophysics , biochemistry , receptor , medicine , gene , construct validity , nursing , patient satisfaction
The membrane topology of α2/δ subunit was investigated utilizing electrophysiological functional assay and specific anti‐α2 antibodies. (a) cRNA encoding a deleted α2/δ subunit was coinjected with α1C subunit of the L‐type calcium channel into Xenopus oocytes. The truncated form, lacking the third putative TM domain (α2/δΔTMIII), failed to amplify the expressed inward currents, normally induced by α 1c coinjected with intact α2/δ subunit. Western blot analysis of α2/δΔTMIII shows the appearance of a degraded α2 protein and no expression of the full‐size two‐TM truncated‐protein. The improper processing of α2/δΔTMIII suggests that the α2/δ is a single TM domain protein and the TM region is positioned at the δ subunit. (b) External application of anti‐α2 antibodies, prepared for an epitope within the alternatively spliced and ‘intracellular’ region, inhibits depolarization induced secretion in PC12, further supporting an external location of the α2 subunit and establishing δ subunit as the only membrane anchor for the extracellular α2 subunit.