ABSTRACT
Highly purified alpha-latrotoxin from the black widow spider venom (alpha-LTX) consists of two polypeptides with mol. wts of 130,000 and 8000 (LMWP). We have isolated two low mol. wt proteins LMWP and LMWP2 from the low mol. wt fraction of this venom. The chemical properties of these proteins and partial amino acid sequence of novel protein LMWP2 were studied. By means of i.v. or intracerebroventricular injections into mice it was shown that low mol. wt components of the venom at concentrations of 2.3 mg/kg and 0.8 mg/kg, respectively, did not possess any direct toxic effect on vertebrates. Injections of each protein into the third thoracic segment of cockroaches Periplaneta americana (doses up to 80 micrograms/g) did not cause lethality or paralysis of insects.
Subject(s)
Spider Venoms/chemistry , Amino Acid Sequence , Animals , Electrophoresis, Polyacrylamide Gel , Hydrolysis , Immunoblotting , Injections, Intravenous , Injections, Intraventricular , Mice , Molecular Sequence Data , Molecular Weight , Periplaneta , Spider Venoms/isolation & purification , Spider Venoms/toxicityABSTRACT
We have studied the action of an alpha-latrotoxin (alpha-LTX) complex of two polypeptides (LTX 130 kDa and low molecular weight protein (LMWP) 8 kDa) and the action of a venom fraction containing LTX with excess LMWP on calcium influx into synaptosomes and PC12 cells as well as on [14C]GABA release from synaptosomes. Both preparations considerably activate calcium influx and stimulate [14C]GABA release from synaptosomes. Preincubation of both preparations with antibodies against a 14 amino acid residue C-terminal peptide of LMWP differentially modulates these effects. Antibodies inhibit induced calcium influx and enhance induced GABA release.
