The α2/δ subunit of voltage sensitive Ca2+ channels is a single transmembrane extracellular protein which is involved in regulated secretion

FEBS Letters

Trus, Michael¹  Halevi, Sarah¹  Wiser, Ofer¹  Giladi, Eli¹  Tobi, Dror¹  Atlas, Daphne¹ 

[1] Department of Biological Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel

关键词: Ca2+ channel;    PC12 cell;    α2 Subunit;    δ Subunit;    Regulated secretion;    Exocytosis;   

DOI  :  10.1016/0014-5793(95)01475-6

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

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.

【 授权许可】

Unknown