SNX-482-A New Class E (R-type) Ca2+ Channel Blocker from the venom of the African tarantula Hysterocrates gigas from Peptides International

SNX-482
A New Class E (R-type) Ca²⁺ Channel Blocker from the
venom of the African tarantula Hysterocrates gigas

Made by the Peptide Institute and available from Peptides International

Voltage dependent calcium channels vary greatly in structure and form. This diversity imparts these channels with a variety of important physiological roles such as the regulation of neuronal function in the central nervous system (i.e., neurotransmission and neurosecretion), as well as cellular metabolism and cell membrane electrical potentials. According to their pharmacological and electrophysiological properties, calcium channels are classified as L-, N-, P/Q, T- and R-type. In the past, a potent and selective blocker for the R-type calcium channels was not available. Recently, a natural R-type (subtype a_1E) calcium channel blocker was discovered in the venom of the African tarantula Hysterocrates gigas, commonly called the Cameroon red baboon spider. Now, this novel 41 amino acid peptide is commercially available from the Peptide Institute. SNX-482 has three disulfide linkages (Cys⁷-Cys²¹, Cys¹⁴-Cys²⁶, and Cys²⁰-Cys³³) and has an IC₅₀ = 15-30 nM in the R-type Ca²⁺ current; it is highly selective showing no effect of Na⁺, K⁺ and L, P/Q, T-type Ca²⁺ currents. It shows only a 30-50% blockage of the N-type Ca²⁺current at high concentrations (300-500 nM). The function of R-type Ca²⁺channels should be better understood by those working with this new peptide.

1. R. Newcomb, B. Szoke, A. Palma, G. Wang, X.-h. Chen, W. Hopkins, R. Cong, J. Miller, L. Ürge, K. Tarczy-Hornoch, J.A. Loo, D.J. Dooley, L. Nádasdi, R. W. Tsien, J. Lemos, and G. Miljanich, Biochemistry, 37, 15353 (1998). (Original)
2. L. Ürge, B. Szoke, D. Silva, P. Tran-Tau, D. Hom, K. Tarczy-Hornoch, and L. Nádasdi, In Peptides 1998, (S. Bajusz and F. Hudecz, eds.), Akadémiai Kiadó, Budapest, pp.748-749 (1998). (S-S Bond)
3. A. Tottene, S. Volsen, and D. Pietrobon, J. Neurosci., 20, 171 (2000). (Pharmacol.)
4. G. Wang, G. Dayanithi, R. Newcomb, and J. R. Lemos, J. Neurosci., 19, 9235 (1999). (Pharmacol.)

CODE

PRODUCT DESCRIPTION

VIAL

USD

PCB-4363-s

NEW!

SNX-482
(Tarantula, Hysterocrates gigas)
Gly-Val-Asp-Lys-Ala-Gly-Cys-Arg-Tyr-Met-Phe-Gly-Gly-
Cys-Ser-Val-Asn-Asp-Asp-Cys-Cys-Pro-Arg-Leu-Gly-
Cys-His-Ser-Leu-Phe-Ser-Tyr-Cys-Ala-Trp-Asp-Leu-
Thr-Phe-Ser-Asp
(Disulfide bonds between Cys⁷-Cys²¹, Cys¹⁴-Cys²⁶, and Cys²⁰-Cys³³)
(M.W. 4495.00)
Class E (R-type) Ca²⁺ Channel Blocker

0.1 mg
vial

330

Specific Channel Type	Channel Blocker	Effective Concentration	Notes
P-type	w -Agatoxin TK	IC₅₀ = 15 nM	Also blocks a Q-type-like Ca²⁺ channel in rat hippocampal neurons with low sensitivity
P-type	w -Agatoxin IVA	K_d = 2 nM	Selective blocker with high affinity
N-type	w -Conotoxin GVIA,	100 nM - 2 m M	Reversibly blocks synapse neurotransmitter release.
	w -Conotoxin MVIIA	100 nM - 1 m M	Highly potent blocker, competes with w -Conotoxin GVIA
	w -Conotoxin SVIB	100 nM - 2 m M	Pre-synaptic blocker.
L-type	Calciseptine	100 nM - 2 m M	Very specific and highly potent.
L-type	Calcicludine	L-type: IC₅₀ = 200 pM	Also blocks N- and P-types to a lesser extent
P/Q-type	w -Conotoxin MVIIC	50 nM - 1 m M	Selective and highly potent
R-type	SNX-482	IC₅₀ = 15 - 30 nM	Specific for Class E subtype
R-type	PLTX-II		Pre-synaptic blocker.

Please contact Peptides International for ordering information.
Peptides International, Inc.
PO Box 24658
Louisville, Kentucky 40224 USA
Phone: 502-266-8787 or 800-777-4779
Fax: 502-267-1FAX (1329)

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