BeKm-1

BeKm-1 toxin is a peptide toxin that has been isolated from the venom of the Central Asian scorpion Buthus eupeus. BeKm-1 toxin has been reported to be a highly selective inhibitor of the human ether-a-go-go ERG1 channel (hERG1). BeKm-1 inhibits hERG1 channels expressed in HEK-293 cells with an IC50 of 3.3 nM, but has no effect at 100 nM on human EAG, human SK1, rat SK2, human IK, human BK, KCNQ1/KCNE1, KCNQ2/KCNQ3, and KCNQ4 channels. It has also minimal effects on rat ELK1 channel. BeKm-1 inhibits the human ERG1 + KCNE1 combination transiently expressed in HEK-293 cells with an IC50 value in the range of 10 to 30 nM. BeKm-1 toxin preferentially blocks human ERG channel through the closed (resting) state, although some open channel blockade is also reported to occur.