Cooperative interactions among subunits of a voltage-dependent potassium channel: Evidence from expression of concatenated cDNAs

Raymond S. Hurst, Michael P. Kavanaugh, Jerrel Yakel, John Adelman, R. Alan North

Research output: Contribution to journalArticle

45 Citations (Scopus)

Abstract

Four copies of the coding sequence for a voltage-dependent potassium channel (RBK1, rat Kv1.1) were ligated contiguously and transcribed in vitro. The resulting RNA encodes four covalently linked subunit domains ([4]RBK1). Injection of this RNA into Xenopus oocytes resulted in the expression of voltage-dependent potassium currents. A single amino acid substitution, Tyr → Val, located within the outer mouth of the pore, introduced into the equivalent position of any of the four domains, reduced affinity for external tetraethylammonium by approximately the same amount. In constructs containing 0, 1, 2, 3, or 4 Tyr residues the free energy of binding tetraethylammonium was linearly related to the number of Tyr residues. A different amino acid substitution, Leu → Ile, located in the S4 region, was made in the equivalent position of one two, three, or four domains. The depolarization required for channel activation increased approximately linearly with the number of Ile residues, whereas models of independent gating of each domain predict marked nonlinearity. Expression of this concatenated channel provides direct evidence that voltage-dependent potassium channels have four subunits positioned symmetrically around a central permeation pathway and that these subunits interact cooperatively during channel activation.

Original languageEnglish (US)
Pages (from-to)23742-23745
Number of pages4
JournalJournal of Biological Chemistry
Volume267
Issue number33
StatePublished - Nov 25 1992

Fingerprint

Tetraethylammonium
Potassium Channels
Amino Acid Substitution
Complementary DNA
RNA
Electric potential
Substitution reactions
Xenopus
Chemical activation
Oocytes
Mouth
Amino Acids
Potassium
Depolarization
Permeation
Free energy
Injections
In Vitro Techniques
rat Kcna1 protein

ASJC Scopus subject areas

  • Biochemistry

Cite this

Cooperative interactions among subunits of a voltage-dependent potassium channel : Evidence from expression of concatenated cDNAs. / Hurst, Raymond S.; Kavanaugh, Michael P.; Yakel, Jerrel; Adelman, John; North, R. Alan.

In: Journal of Biological Chemistry, Vol. 267, No. 33, 25.11.1992, p. 23742-23745.

Research output: Contribution to journalArticle

Hurst, Raymond S. ; Kavanaugh, Michael P. ; Yakel, Jerrel ; Adelman, John ; North, R. Alan. / Cooperative interactions among subunits of a voltage-dependent potassium channel : Evidence from expression of concatenated cDNAs. In: Journal of Biological Chemistry. 1992 ; Vol. 267, No. 33. pp. 23742-23745.
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