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 IC50 of 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.
Keywords:
Apamin block; Jurkat; Kv1.3 channel; Lymphocytes; SK channel.
MeSH terms
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Apamin / toxicity*
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Electrophysiological Phenomena / drug effects
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HEK293 Cells
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Humans
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Inhibitory Concentration 50
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Kv1.3 Potassium Channel / antagonists & inhibitors*
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Kv1.3 Potassium Channel / metabolism
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Neurotoxins / toxicity*
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Pancreatitis-Associated Proteins
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Potassium Channel Blockers / toxicity*
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Potassium Channels, Calcium-Activated / antagonists & inhibitors*
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Potassium Channels, Calcium-Activated / metabolism
Substances
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Kv1.3 Potassium Channel
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Neurotoxins
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Pancreatitis-Associated Proteins
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Potassium Channel Blockers
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Potassium Channels, Calcium-Activated
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REG3A protein, human
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Apamin