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Tamapin, a Venom Peptide From the Indian Red Scorpion (Mesobuthus Tamulus) That Targets Small Conductance Ca2+-activated K+ Channels and Afterhyperpolarization Currents in Central Neurons

Tamapin, a Venom Peptide From the Indian Red Scorpion (Mesobuthus Tamulus) That Targets Small Conductance Ca2+-activated K+ Channels and Afterhyperpolarization Currents in Central Neurons

Paola Pedarzani, Dieter D'hoedt, Kevina B Doorty, Jonathan D F Wadsworth, Jeremiah S Joseph, Kandiah Jeyaseelan, R Manjunatha Kini, S V Gadre, S M Sapatnekar, Martin Stocker, Peter N Strong

J Biol Chem. 2002 Nov 29;277(48):46101-9.

PMID: 12239213

Abstract:

The biophysical properties of small conductance Ca(2+)-activated K(+) (SK) channels are well suited to underlie afterhyperpolarizations (AHPs) shaping the firing patterns of a conspicuous number of central and peripheral neurons. We have identified a new scorpion toxin (tamapin) that binds to SK channels with high affinity and inhibits SK channel-mediated currents in pyramidal neurons of the hippocampus as well as in cell lines expressing distinct SK channel subunits. This toxin distinguished between the SK channels underlying the apamin-sensitive I(AHP) and the Ca(2+)-activated K(+) channels mediating the slow I(AHP) (sI(AHP)) in hippocampal neurons. Compared with related scorpion toxins, tamapin displayed a unique, remarkable selectivity for SK2 versus SK1 ( approximately 1750-fold) and SK3 ( approximately 70-fold) channels and is the most potent SK2 channel blocker characterized so far (IC(50) for SK2 channels = 24 pm). Tamapin will facilitate the characterization of the subunit composition of native SK channels and help determine their involvement in electrical and biochemical signaling.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
IAR4245389	Tamapin			Price

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