Inhibitor for Cation-Selective Stretch-Activated Channels / Atrial Fibrillation Inhibiting Peptide
Mechanosensitive ion channels (MSCs) are ubiquitous from unicellular to multicellular organisms and participate in numerous physiological processes including touch and pain sensation, salt and fluid balance, blood pressure control, cell volume regulation, and turgor control [Physiol. Rev., 81, 685 (2001)]. Analysis of the functions mediated by these channels can be performed by utilizing a specific blocker with high selectivity to the particular channels. In the research of stretch-activated ion channels (SACs), one of MSCs, cationic metal, Gd3+, and cationic compounds including amiloride, and cationic antibiotics have been used as blockers, but were reported to be non-selective (lack of specificity). In 2000, Professor F. Sachs of State University of New York at Buffalo discovered a peptidic toxin named GsMTx-4 in the venom of the tarantula Grammostola spatulata and repoted it to possess a specific blocking activity for stretch-activated currents[J. Gen. Physiol., 115, 583 (2000)]. GsMTx-4 blocks: i) SAC current in outside-out patches from adult rat astrocytes (Kd=630 nM); ii) swelling-activated whole cell current (an inwardly rectifying cation selective current) in cardiac myocytes at 400 nM (but not an outwardly rectifying Cl– current); and iii) MSC current in normal rat kidney cells at 5 μM [[J. Gen. Physiol., 115, 583 (2000), Toxicon, 42, 263 (2003)]. Also, this peptide inhibits the atrial fibrillation associated with dilatation at 170 nM (anti-arrhythmic activity)[Physiol. Rev., 81, 685 (2001), Nature, 409, 35 (2001)].
Gly-Cys-Leu-Glu-Phe-Trp-Trp-Lys-Cys-Asn- Pro-Asn-Asp-Asp-Lys-Cys-Cys-Arg-Pro-Lys- Leu-Lys-Cys-Ser-Lys-Leu-Phe-Lys-Leu-Cys- Asn-Phe-Ser-Phe-NH2 (Disulfide bonds between Cys2-Cys17, Cys9-Cys23, and Cys16-Cys30)
Primary sequence of GsMTx-4 has been clarified recently by cDNA cloning to be a 34-residue peptide possessing a post-translationally modified amide structure at its carboxyl-terminus[Toxicon, 42, 263 (2003)]. Three disulfide linkages in the molecule were connected in the pattern of Cys1-Cys4, Cys2-Cys5, and Cys3-Cys6 (Cys numberings from the amino-terminus) during the determination of its solution structure, indicating that GsMTx-4 is a member of “inhibitor cystine knot” peptides[J. Biol. Chem., 277, 34443 (2002)]. GsMTx-4 should prove to be a useful tool for the study of the biological events initiated by the activation and inactivation of SACs.
|4393-s||GsMTx-4||0.1 mg vial||22,000|