RT Journal Article
SR Electronic
T1 Anuroctoxin, a New Scorpion Toxin of the α-KTx 6 Subfamily, Is Highly Selective for Kv1.3 over IKCa1 Ion Channels of Human T Lymphocytes
JF Molecular Pharmacology
JO Mol Pharmacol
FD American Society for Pharmacology and Experimental Therapeutics
SP 1034
OP 1044
DO 10.1124/mol.104.007187
VO 67
IS 4
A1 Bagdáany, Miklós
A1 Batista, Cesar V. F.
A1 Valdez-Cruz, Norma A.
A1 Somodi, Sándor
A1 de la Vega, Ricardo C. Rodriguez
A1 Licea, Alexei F.
A1 Varga, Zoltáan
A1 Gáspár, Rezső
A1 Possani, Lourival D.
A1 Panyi, György
YR 2005
UL http://molpharm.aspetjournals.org/content/67/4/1034.abstract
AB The physiological function of T lymphocytes can be modulated selectively by peptide toxins acting on Kv1.3 K+ channels. Because Kv1.3-specific peptide toxins are considered to have a significant therapeutic potential in the treatment of autoimmune diseases, the discovery of new toxins is highly motivated. Through chromatographic procedures and electrophysiological assays, using patch-clamp methodology, the isolation of a novel peptide named anuroctoxin was accomplished using the venom of the Mexican scorpion Anuroctonus phaiodactylus. It has 35 amino acid residues with a molecular weight of 4082.8, tightly bound by four disulfide bridges whose complete covalent structure was determined. It has a pyroglutamic acid at the N-terminal region and an amidated C-terminal residue. Sequence comparison and phylogenetic clustering analysis classifies anuroctoxin into subfamily 6 of the α-KTx scorpion toxins (systematic name, α-KTx 6.12). Patch-clamp experiments show that anuroctoxin is a high-affinity blocker of Kv1.3 channels of human T lymphocytes with a Kd of 0.73 nM, and it does not block the Ca2+-activated IKCa1 K+ channels. These two channels play different but important roles in T-lymphocyte activation. Furthermore, the toxin practically does not inhibit Shaker IR, mKv1.1, and rKv2.1 channels, whereas the affinity of anuroctoxin for hKv1.2 is almost an order of magnitude smaller than for Kv1.3. The pharmacological profile and the selectivity of this new toxin for Kv1.3 over IKCa1 may provide an important tool for the modulation of the immune system, especially in cases in which selective inhibition of Kv1.3 is required.