Novel spider toxin slows down the activation kinetics of P-type Ca2+ channels in Purkinje neurons of rat |
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Authors: | Fisyunov Alexander Pluzhnikov Kirill Molyavka Anton Grishin Eugene Lozovaya Natalia Krishtal Oleg |
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Institution: | Department of Cellular Membranology, A.A. Bogomoletz Institute of Physiology, Bogomoletz Street 4, Kiev 01024, Ukraine. |
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Abstract: | We have identified a novel polypeptide toxin (Lsp-1) from the venom of the spider Lycosa (LS). Its effect has been examined on the P-type calcium channels in Purkinje neurons, using whole-cell patch-clamp. This toxin (at saturating concentration 7 nM) produces prominent (four-fold) deceleration of the activation kinetics and partial (71+/-6%) decrease of the amplitude of P-current without affecting either deactivation or inactivation kinetics. These effects are not use-dependent. They are partially reversible within a minute upon the wash-out of the toxin. Intracellular perfusion of Purkinje neurons with 100 microM of GDP or 2 microM of GTPgammaS, as well as strong depolarising pre-pulses (+100 mV), do not eliminate the action of Lsp-1 on P-channels indicating that down-modulation via guanine nucleotide-binding proteins (G-proteins) is not involved in the observed phenomenon. In view of extremely high functional significance of P-channels, the toxin can be suggested as a useful pharmacological tool. |
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