| Structural highlights
Function
[KA142_MESMA] Inhibits potassium channels. May be active towards small conductance calcium-activated potassium channels (KCNN, SK), and less active towards voltage-gated potassium channels (Kv/KCN).[1] [2]
Publication Abstract from PubMed
A natural K+ channel blocker, BmKK2 (a member of scorpion toxin subfamily alpha-KTx 14), which is composed of 31 amino acid residues and purified from the venom of the Chinese scorpion Buthus martensi Karsch, was characterized using whole-cell patch-clamp recording in rat hippocampal neurons. The three dimensional structure of BmKK2 was determined with two-dimensional NMR spectroscopy and molecular modelling techniques. In solution this toxin adopted a common alpha/beta-motif, but showed distinct local conformation in the loop between alpha-helix and beta-sheet in comparison with typical short-chain scorpion toxins (e.g., CTX and NTX). Also, the alpha helix is shorter and the beta-sheet element is smaller (each strand consisted only two residues). The unusual structural feature of BmKK2 was attributed to the shorter loop between the alpha-helix and beta-sheet and the presence of two consecutive Pro residues at position 21 and 22 in the loop. Moreover, two models of BmKK2/hKv1.3 channel and BmKK2/rSK2 channel complexes were simulated with docking calculations. The results demonstrated the existence of a alpha-mode binding between the toxin and the channels. The model of BmKK2/rSK2 channel complex exhibited favorable contacts both in electrostatic and hydrophobic, including a network of five hydrogen bonds and bigger interface containing seven pairs of inter-residue interactions. In contrast, the model of BmKK2/hKv1.3 channel complex, containing only three pairs of inter-residue interactions, exhibited poor contacts and smaller interface. The results well explained its lower activity towards Kv channel, and predicted that it may prefer a type of SK channel with a narrower entryway as its specific receptor.
Solution structure of BmKK2, a new potassium channel blocker from the venom of chinese scorpion Buthus martensi Karsch.,Zhang N, Li M, Chen X, Wang Y, Wu G, Hu G, Wu H Proteins. 2004 Jun 1;55(4):835-45. PMID:15146482[3]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Zhang N, Li M, Chen X, Wang Y, Wu G, Hu G, Wu H. Solution structure of BmKK2, a new potassium channel blocker from the venom of chinese scorpion Buthus martensi Karsch. Proteins. 2004 Jun 1;55(4):835-45. PMID:15146482 doi:http://dx.doi.org/10.1002/prot.20117
- ↑ Li MH, Zhang NX, Chen XQ, Wu G, Wu H, Hu GY. Purification and pharmacological characterization of BmKK2 (alpha-KTx 14.2), a novel potassium channel-blocking peptide, from the venom of Asian scorpion Buthus martensi Karsch. Toxicon. 2004 Jun 15;43(8):895-900. PMID:15208022 doi:http://dx.doi.org/10.1016/j.toxicon.2003.11.028
- ↑ Zhang N, Li M, Chen X, Wang Y, Wu G, Hu G, Wu H. Solution structure of BmKK2, a new potassium channel blocker from the venom of chinese scorpion Buthus martensi Karsch. Proteins. 2004 Jun 1;55(4):835-45. PMID:15146482 doi:http://dx.doi.org/10.1002/prot.20117
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