Determinants of apamin and d-tubocurarine block in SK potassium channels

Takahiro M. Ishii, James Maylie, John Adelman

Research output: Contribution to journalArticle

216 Citations (Scopus)

Abstract

Small conductance calcium-activated potassium channels show a distinct pharmacology. Some, but not all, are blocked by the peptide toxin apamin, and apamin-sensitive channels are also blocked by d-tubocurarine. Cloned SK channels (small conductance calcium-activated potassium channel) recapitulate these properties. We have investigated the structural basis for these differences and found that two amino acid residues on either side of the deep pore are the primary determinants of sensitivity to apamin and differential block by d-tubocurarine. Therefore, the pharmacology of SK channels compared with other potassium channels correlates with structural differences in the outer pore region. However, introduction of a tyrosine residue in the position analogous to that which determines sensitivity to external tetraethylammonium for voltage-gated potassium channels endows SK channels with an equivalent tetraethylammonium sensitivity, indicating that the outer vestibules of the pores are similar. The pharmacology of channels formed in oocytes coinjected with SK1 and SK2 mRNAs, or with SK1-SK2 dimer mRNA, show that SK subunits may form heteromeric channels.

Original languageEnglish (US)
Pages (from-to)23195-23200
Number of pages6
JournalJournal of Biological Chemistry
Volume272
Issue number37
DOIs
StatePublished - 1997

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Small-Conductance Calcium-Activated Potassium Channels
Apamin
Tubocurarine
Tetraethylammonium
Pharmacology
Voltage-Gated Potassium Channels
Messenger RNA
Potassium Channels
Dimers
Oocytes
Tyrosine
Amino Acids
Peptides

ASJC Scopus subject areas

  • Biochemistry

Cite this

Determinants of apamin and d-tubocurarine block in SK potassium channels. / Ishii, Takahiro M.; Maylie, James; Adelman, John.

In: Journal of Biological Chemistry, Vol. 272, No. 37, 1997, p. 23195-23200.

Research output: Contribution to journalArticle

Ishii, Takahiro M. ; Maylie, James ; Adelman, John. / Determinants of apamin and d-tubocurarine block in SK potassium channels. In: Journal of Biological Chemistry. 1997 ; Vol. 272, No. 37. pp. 23195-23200.
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