Abstract
1. Block by external tetraethylammonium (TEA) was examined on currents carried by potassium (K+) and sodium (Na+) through the cloned delayed rectifier K+ channel Kv2.1. 2. In the presence of high intracellular K+ and high extracellular Na+, currents through the Kv2.1 channel were carried almost exclusively by K+. In the absence of both intracellular and extracellular K+, large currents were carried by Na+ through the Kv2.1 channel. 3. External application of 30 mM TEA blocked K+ currents through Kv2.1 by 87%. The same external concentration of TEA had no effect on Na+ currents through this channel. 4. As the K+ concentration was increased between 0 and 140 mM, the percentage of current blocked by TEA progressively increased from 0 to 87%. 5. These data indicate that block of K+ channels by external TEA depends on the permeating ion. Furthermore, these data indicate that in the presence of Na+ and absence of K+, TEA does not bind to the channel, and that addition of low concentrations of K+ facilitates TEA binding.
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- Armstrong C. M., Hille B. The inner quaternary ammonium ion receptor in potassium channels of the node of Ranvier. J Gen Physiol. 1972 Apr;59(4):388–400. doi: 10.1085/jgp.59.4.388. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Callahan M. J., Korn S. J. Permeation of Na+ through a delayed rectifier K+ channel in chick dorsal root ganglion neurons. J Gen Physiol. 1994 Oct;104(4):747–771. doi: 10.1085/jgp.104.4.747. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hamill O. P., Marty A., Neher E., Sakmann B., Sigworth F. J. Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patches. Pflugers Arch. 1981 Aug;391(2):85–100. doi: 10.1007/BF00656997. [DOI] [PubMed] [Google Scholar]
- Heginbotham L., MacKinnon R. The aromatic binding site for tetraethylammonium ion on potassium channels. Neuron. 1992 Mar;8(3):483–491. doi: 10.1016/0896-6273(92)90276-j. [DOI] [PubMed] [Google Scholar]
- Ikeda S. R., Soler F., Zühlke R. D., Joho R. H., Lewis D. L. Heterologous expression of the human potassium channel Kv2.1 in clonal mammalian cells by direct cytoplasmic microinjection of cRNA. Pflugers Arch. 1992 Nov;422(2):201–203. doi: 10.1007/BF00370422. [DOI] [PubMed] [Google Scholar]
- Jan L. Y., Jan Y. N. Voltage-sensitive ion channels. Cell. 1989 Jan 13;56(1):13–25. doi: 10.1016/0092-8674(89)90979-3. [DOI] [PubMed] [Google Scholar]
- Kavanaugh M. P., Hurst R. S., Yakel J., Varnum M. D., Adelman J. P., North R. A. Multiple subunits of a voltage-dependent potassium channel contribute to the binding site for tetraethylammonium. Neuron. 1992 Mar;8(3):493–497. doi: 10.1016/0896-6273(92)90277-k. [DOI] [PubMed] [Google Scholar]
- MacKinnon R. Determination of the subunit stoichiometry of a voltage-activated potassium channel. Nature. 1991 Mar 21;350(6315):232–235. doi: 10.1038/350232a0. [DOI] [PubMed] [Google Scholar]
- Stühmer W., Ruppersberg J. P., Schröter K. H., Sakmann B., Stocker M., Giese K. P., Perschke A., Baumann A., Pongs O. Molecular basis of functional diversity of voltage-gated potassium channels in mammalian brain. EMBO J. 1989 Nov;8(11):3235–3244. doi: 10.1002/j.1460-2075.1989.tb08483.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Taglialatela M., Vandongen A. M., Drewe J. A., Joho R. H., Brown A. M., Kirsch G. E. Patterns of internal and external tetraethylammonium block in four homologous K+ channels. Mol Pharmacol. 1991 Aug;40(2):299–307. [PubMed] [Google Scholar]
- Yellen G., Jurman M. E., Abramson T., MacKinnon R. Mutations affecting internal TEA blockade identify the probable pore-forming region of a K+ channel. Science. 1991 Feb 22;251(4996):939–942. doi: 10.1126/science.2000494. [DOI] [PubMed] [Google Scholar]
- Zhu Y., Ikeda S. R. Anomalous permeation of Na+ through a putative K+ channel in rat superior cervical ganglion neurones. J Physiol. 1993 Aug;468:441–461. doi: 10.1113/jphysiol.1993.sp019781. [DOI] [PMC free article] [PubMed] [Google Scholar]