Apamin
- 貨號 Cat. No.
- A-200
- 規格 Size
- 0.2 mg 5x0.2mg
Description
Apamin
Small conductance Ca2+ activated K+ channels (SK) blocker
| Product#: | A-200 |
| Sizes: |
| 0.2 mg |
| 5 x 0.2 mg |
| M.W.: | 2027 |
| Sequence: | H-Cys1-Asn-Cys3-Lys-Ala-Pro-Glu-Thr-Ala-Leu-Cys11-Ala-Arg-Arg-Cys15-Gln-Gln-His-NH2 (disulfide bonds: 1 to 11; 3 to 15) |
| Purity: | >98% |
| Bioassay: |
| The biological activity was examined on Xenopus oocytes expressing hKCa2.1 and rKCa2.2 (human SK1 and rat SK2 ). Channels were activated by intracellular Ca2+ injection. |
 |
| Legend: Voltage clamped whole oocyte current was recorded continuously under low Cl- concentration at 5 mV holding potential. At the indicated time 10 nl of 100 mM Ca2+ was injected into the oocyte and an outward current developed. A minute later 3 mM Apamin was perfused to the bath, resulting in about 60% inhibition in the amplitude of this Ca2+ dependent current, which nearly completely recovered upon toxin wash. |
| References: |
1. | Gauldie, J. et al. (1976) Eur. J. Biochem. 61,1369. |
2. | Logsdon, N.J. et al. (1997) J. Biol. Chem. 272, 32723. |
3. | Shah M. and Haylett D.G. (2000) Br. J. Pharm. 129, 627. |
4. | Strobaek D. et al. (2000) Br. J. Pharm. 129, 991. |
5. | Barfod, E.T. et al. (2001) Am. J. Physiol. 280, C836. |
6. | Desai, R. et al. (2000) J. Biol. Chem. 275, 39954. |
7. | Husseini, R. et al. (2001) J. Physiol. 535, 323. |
8. | Kong, I.D. et al. (2000) Am. J. Physiol. 278, C352. |
9. | Nagayama, T. et al. (2000) Am. J. Physiol. 279, R1731. |
Apamin is a natural peptide isolated and purified from Apis mellifera bee venom. Apamin blocks small conductance Ca2+ activated K+ channels (SK). It is specific for the SK1-3 isoforms, but ineffective in blocking other calcium activated K+ channels (see for example)2. In mammalian cell lines Apamin blocks expressed hSK1 with an IC50 of ~10nM 3, rSK1 and rSK2 with IC50 of ~3 and <1 nM respectively 4 and liver rSK3 with IC50 <1nM.5 In Jurkat T-cells 5nM blocks 70% of hSK2 currents.6 Blocking these channels with Apamin influences slow afterhyperpolarization in neurons (see for example)7, as well as smooth muscle contraction8 and catecholamine secretion in adrenal gland.9 Electrophysiology, application of long (~400ms) voltage ramps, covering the whole physiological range (-160 to +40mV), in the whole cell patch-clamp or voltage clamp configurations, before and after bath perfusion of the drug, allows the detection of the blocked channel currents (by comparison) (see for example).1