Pumiliotoxin B (PTX-B), an alkaloid that has cardiotonic and myotonic activity, increases sodium influx in guinea pig cerebral cortical synaptoneurosomes. In the presence of scorpion venom (Leiurus) or purified alpha-scorpion toxin, the PTX-B-induced sodium influx is enhanced severalfold. PTX-B alone has no effect on sodium flux in N18 neuroblastoma cells but, in the presence of alpha-scorpion ...

Purified scorpion toxin (Leiurus quinquestriatus) slows inactivation of sodium channels in frog muscle at concentrations in the range of 17-170 nM. Mono[125I]iodo scorpion toxin binds to a single class of sites in frog sartorius muscle with a dissociation constant of 14 nM and a binding capacity of 13 fmol/mg wet weight. Specific binding is inhibited more than 90% by 3 microM sea anemone toxin ...

Toxin II isolated from the sea anemone Anemonia sulcata enhances activation of the action potential sodium ionophore of electrically excitable neuroblastoma cells by veratridine and batrachotoxin. This heterotropic cooperative effect is identical to that observed previously with scorpion toxin but occurs at a 110-fold higher concentration. Depolarization of the neuroblastoma cells inhibits the ...

Depolarization of neuroblastoma cells causes a 70-fold increase in the apparent dissociation constant KD for scorpion toxin enhancement of activation of the action potential Na+ ionophore by veratridine and a large increase in the rate of reversal of scorpion toxin action. Depolarization also inhibits binding of 125I-labeled scorpion toxin to a small number of saturable binding sites on electri...

Scorpion mono[‘2sIJiodotoxin binds to a single class of receptor sites associated with voltage-sensitive sodium channels in synaptic nerve ending particles (synaptosomes) with a KD of approximately 3 11~. Scorpion toxin binding is inhibited by depolarization of the synaptosomes with K+ or gramicidin or by lysis of the synaptosomes. Scorpion toxin binding is enhanced by batrachotoxin, veratridin...

Iodination of toxin II from the sea anemone Anemonia sulcata gives a labeled monoiododerivative that retains 80% of the original neurotoxicity. This derivative binds specifically to rat brain synaptosomes at 20 degrees C and pH 7.4 with a second-order rate constant of association ka = 4.6 x 10(4) M-1 sec-1 and a first-order rate constant of dissociation kd = 1.1 x 10(-2) sec-1. The binding occu...

Photoreactive derivatives of alpha- and beta-scorpion toxins have been used to analyze the subunit composition of Na+ channels in rat brain. In synaptosomes, both types of toxins preferentially labeled (greater than 85%) a component of 34,000 Da and, at a lower level, another component of 300,000 Da. Reduction of disulfide bridges shifted this latter band from 300,000 Da to 272,000 Da but did n...

Scorpion toxin enhances activation of the action potential Na+ ionophore by the alkaloid neurotoxins veratridine, batrachotoxin, and aconitine. The pure toxin can be iodinated in a lactoperoxidase-catalyzed reaction. Both the monoiodoand diiodotoxin derivatives retain physiologic activity. Both monoiodoand diiodoscorpion toxin bind to a single class of saturable binding sites in electrically ex...

background: the mesobuthus eupeus scorpion venoms are known to contain α-toxin peptides, many of which interfere with k+ ion channel function. these toxin peptides have important value in  the pharmacology and physiology studies of specific k+ channel of cells. objectives: given the  lack of information of the molecular biology of peptides in the toxin of iranian scorpions, the aim of this stud...

Venom of the scorpion Leiurus quinquestriatus acts cooperatively with the alkaloids veratridine, aconitine, and batrachotoxin in activating the action potential Na+ ionophore. A small (Mr = 6700), basic (pI approximately 9.8), toxic polypeptide purified approximately 80-fold from this venom by ion exchange chromatography appears homogeneous by gel electrophoresis and isoelectric focusing and, l...