Margatoxin

Margatoxin (MgTx) is a 39 amino-acid-long peptide stabilized by 3 disulfide bridges with a molecular weight of 4185, isolated from the venom of the scorpion Centruroides margaritatus. This peptide is widely used in the field of ion channel research. Margatoxin is considered as a high affinity and selective inhibitor of the Kv1.3 channel, however, a comprehensive study of its selectivity with electrophysiological methods has not been published yet.  >> Read More

When MgTx was isolated and its high affinity interaction with Kv1.3 was precisely characterized it was only tested on a limited number of channels excluding Kv1.1, Kv1.2 and Kv1.4 channels, those with high sequence homology to Kv1.3. Later the authors who described MgTx and other workgroups refer to the peptide as potent blocker of Kv1.1, Kv1.2 and Kv1.3 channels, whereas the references do not describe or contain any information about the interaction of MgTx and the Kv1.1 or Kv1.2 channels. Without the precise characterization of the selectivity profile of MgTx, results from radioactively labeled MgTx binding assays, observed potassium current block or other biological effects of the peptide may not be considered as a direct proof of Kv1.3 expression. In addition, MgTx shares high sequence homology with other scorpion peptides that block both Kv1.3 and Kv1.2 channels with high affinity (Noxiustoxin, Css20) suggesting that MgTx may be a non-selective peptide as well.

Margatoxin is a non-selective inhibitor of human Kv1.3 K+channels

Margatoxin (MgTX), a 39-amino acid peptide from Centruroides margaritatus, is a potent inhibitor of lymphocyte KV channels. The binding of monoiodotyrosinyl margatoxin ([¹²⁵I]MgTX) to plasma membranes prepared from either Jurkat cells, a human leukemic T cell line, or CHO cells stably transfected with the Shaker-type voltage-gated K+ channel, KV1.3, has been used to investigate the properties of lymphocyte KVchannels. These data were compared with [¹²⁵I]MgTX binding to heterotetrameric KV channels in rat brain synaptic plasma membranes.

Margatoxin Binds to a Homomultimer of KV1.3 Channels in Jurkat Cells. Comparison with KV1.3 Expressed in CHO Cells