title: The small neurotoxin apamin blocks not only small conductance Ca2+activated K+channels (SK type) but also the voltage dependent Kv1.3 channel.
abstract: Apamin is frequently used as a specific blocker of small-conductance Ca2+-activated (SK type) K+channels. Here we show that the small neurotoxin is not as specific as anticipated. It is also a high-affinity inhibitor with an IC50of 13 nM of the Kv1.3 channel; it blocks the latter with potency similar to the Kv1.3 blocker PAP-1. Since SK type channels and Kv1.3 channels are frequently coexpressed in different tissues such as cells of the immune system, apamin must be used with caution as a pharmacological tool.
authors.affiliation: Department of Biology, Plant Membrane Biophysics, Technische Universität Darmstadt, Schnittspahnstrasse 3, 64287, Darmstadt, Germany.
authors.forename: Patrick
authors.initials: P
authors.lastname: Voos
authors.affiliation: Department of Biology, Plant Membrane Biophysics, Technische Universität Darmstadt, Schnittspahnstrasse 3, 64287, Darmstadt, Germany.
authors.forename: Mehtap
authors.initials: M
authors.lastname: Yazar
authors.affiliation: Department of Biology, Plant Membrane Biophysics, Technische Universität Darmstadt, Schnittspahnstrasse 3, 64287, Darmstadt, Germany.
authors.forename: René
authors.initials: R
authors.lastname: Lautenschläger
authors.affiliation: Department of Biology, Plant Membrane Biophysics, Technische Universität Darmstadt, Schnittspahnstrasse 3, 64287, Darmstadt, Germany.
authors.forename: Oliver
authors.initials: O
authors.lastname: Rauh
authors.affiliation: Department of Biology and CNR IBF-Mi, Università degli Studi di Milano, Milan, Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Moroni
authors.affiliation: Department of Biology, Plant Membrane Biophysics, Technische Universität Darmstadt, Schnittspahnstrasse 3, 64287, Darmstadt, Germany. thiel@bio.tu-darmstadt.de.
authors.forename: Gerhard
authors.initials: G
authors.lastname: Thiel
mesh_terms: D001030:Apamin / Q000633:toxicity*; D055724:Electrophysiological Phenomena / Q000187:drug effects; D057809:HEK293 Cells; D006801:Humans; D020128:Inhibitory Concentration 50; D051664:Kv1.3 Potassium Channel / Q000037:antagonists & inhibitors* / Q000378:metabolism; D009498:Neurotoxins / Q000633:toxicity*; D000073718:Pancreatitis-Associated Proteins; D026902:Potassium Channel Blockers / Q000633:toxicity*; D024681:Potassium Channels, Calcium-Activated / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: D051664:Kv1.3 Potassium Channel; D009498:Neurotoxins; D000073718:Pancreatitis-Associated Proteins; D026902:Potassium Channel Blockers; D024681:Potassium Channels, Calcium-Activated; C000612141:REG3A protein, human; D001030:Apamin
keywords: Apamin block; Jurkat; Kv1.3 channel; Lymphocytes; SK channel