BACKGROUND The hERG potassium channel can modulate the proliferation of the chronic myelogenous leukemic K562 cells, and its role in the erythroid differentiation of K562 cells still remains unclear. PRINCIPAL FINDINGS The hERG potassium channel blockage by a new 36-residue scorpion toxin BmKKx2, a potent hERG channel blocker with IC50 of 6.7 ± 1.7 nM, enhanced the erythroid differentiation o...

Several naturally occurring polypeptide neurotoxins target specific sites on the voltage-gated sodium channels. Of these, the gating modifier toxins alter the behavior of the sodium channels by stabilizing transient intermediate states in the channel gating pathway. Here we have used an integrated approach that combines electrophysiological and spectroscopic measurements to determine the struct...

The voltage-dependent action of several scorpion a-toxins on Na channels was studied in toad myelinated nerve under voltage clamp. These toxins slow the declining phase of macroscopic Na current, apparently by inhibiting an irreversible channel inactivation step and thus permitting channels to reopen from a closed state in depolarized membranes. In this article, we describe the rapid reversal o...

Sodium channels in cultured neural cells were localized by light microscopic autoradiography of specifically bound 125I-scorpion toxin. Ninety percent of the cell-bound 125I-scorpion toxin was associated specifically with sodium channels as assessed by the blocking of autoradiographic labeling by unlabeled scorpion toxin and by depolarization. Sodium channels were distributed uniformly in the s...

The intense pain induced by scorpion sting is a frequent clinical manifestation. To date, there is no established protocol with significant efficacy to alleviate the pain induced by scorpion envenomation. One of the important reasons is that, little information on pain-inducing compound from scorpion venoms is available. Here, a pain-inducing peptide (BmP01) has been identified and characterize...

Shaker potassium channels from Drosophila are composed of four identical subunits. The contribution of a single subunit to the inactivation gating transition was investigated. Channels carrying a specific mutation in a single subunit can be labeled in a heterogeneous population and studied quantitatively with scorpion toxin sensitivity as a selection tag. Linkage within a single subunit of a mu...

The voltage-dependent action of several scorpion alpha-toxins on Na channels was studied in toad myelinated nerve under voltage clamp. These toxins slow the declining phase of macroscopic Na current, apparently by inhibiting an irreversible channel inactivation step and thus permitting channels to reopen from a closed state in depolarized membranes. In this article, we describe the rapid revers...

The voltage-dependent action of several scorpion a-toxins on Na channels was studied in toad myelinated nerve under voltage clamp. These toxins slow the declining phase of macroscopic Na current, apparently by inhibiting an irreversible channel inactivation step and thus permitting channels to reopen from a closed state in depolarized membranes. In this article, we describe the rapid reversal o...

Maurocalcine (MCa) is a 33-amino-acid residue peptide toxin isolated from the scorpion Scorpio maurus palmatus. External application of MCa to cultured myotubes is known to produce Ca2+ release from intracellular stores. MCa binds directly to the skeletal muscle isoform of the ryanodine receptor, an intracellular channel target of the endoplasmic reticulum, and induces long lasting channel open...

A variety of scorpion venoms and purified toxins were tested for effects on ion channels in human T lymphocytes, a human T leukemia cell line (Jurkat), and murine thymocytes, using the whole-cell patch-clamp method. Nanomolar concentrations of charbdotoxin (CTX), a purified peptide component of Leiurus quinquestriatus venom known to block Ca2+-activated K+ channels from muscle, blocked "type n"...