The small neurotoxin apamin blocks not only small conductance Ca2+ activated K+ channels (SK type) but also the voltage dependent Kv1.3 channel

• DOI: 10.1007/s00249-016-1196-0
• Publication Date: 2017-01-20T09:20:20Z
• Authors: Patrick Voos; Mehtap Yazar; René Lautenschläger; Oliver Rauh; Anna Moroni; Gerhard Thiel
• Keywords: Apamin; Neurotoxin; SK channel

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.