 Cloned SK2 are most sensitive for Apamin in binding assays and physiological recordings.However, tamapin displaces Apamin in binding assays and is therefore a stronger toxin with respect to Apamin.SK 1 and SK 3 are only affected with a high concentration of tapamin and therefore this toxin inhibits SK2 with the highest affinity, SK3 intermediate and the lowest affinity for SK1 channels.