Single-channel properties of the reconstituted voltage-regulated Na channel isolated from the electroplax of Electrophorus electricus.

R. L. Rosenberg, S. A. Tomiko, W. S. Agnew

Research output: Contribution to journalArticlepeer-review

Abstract

The tetrodotoxin-binding protein purified from electroplax of Electrophorus electricus has been reincorporated into multilamellar vesicles that were used for patch recording. When excised patches of these reconstituted membranes were voltage clamped in the absence of neurotoxins, voltage-dependent single-channel currents were recorded. These displayed properties qualitatively and quantitatively similar to those reported for Na channels from nerve and muscle cells, including uniform single-channel conductances of the appropriate magnitude (approximately equal to 11 pS in 95 mM Na+), mean open times of approximately equal to 1.9 msec, and 7-fold selectively for Na+ over K+. Currents averaged from many depolarizations showed initial voltage-dependent activation and subsequent inactivation. In the presence of batrachotoxin, channels were observed with markedly different properties, including conductances of 20-25 pS (95 mM Na+), mean open times of approximately equal to 28 msec, and no indication of inactivation. Collectively, these findings indicate that the tetrodotoxin-binding protein of electroplax is a voltage-regulated sodium channel.

Original languageEnglish (US)
Pages (from-to)5594-5598
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume81
Issue number17
DOIs
StatePublished - Sep 1984
Externally publishedYes

ASJC Scopus subject areas

  • General

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