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SOLUTION STRUCTURE OF THE POTASSIUM CHANNEL INHIBITOR AGITOXIN 2: CALIPER FOR PROBING CHANNEL GEOMETRYSOLUTION STRUCTURE OF THE POTASSIUM CHANNEL INHIBITOR AGITOXIN 2: CALIPER FOR PROBING CHANNEL GEOMETRY
Structural highlights
FunctionKAX32_LEIHE Potent inhibitor of the Shaker potassium channels and its mammalian homologs (Kv1.1/KCNA1, Kv1.3/KCNA3, Kv1.6/KCNA6) (Ki<1 nM for all channels) (PubMed:20007782, PubMed:8204618). Also blocks Kv1.2/KCNA2 (IC(50)=26.8 nM) (PubMed:20007782, PubMed:8204618). It also shows a weak interaction with nicotinic acetylcholine receptors (nAChR), suggesting it may weakly inhibit it (PubMed:31276191).[1] [2] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe structure of the potassium channel blocker agitoxin 2 was solved by solution NMR methods. The structure consists of a triple-stranded antiparallel beta-sheet and a single helix covering one face of the beta-sheet. The cysteine side chains connecting the beta-sheet and the helix form the core of the molecule. One edge of the beta-sheet and the adjacent face of the helix form the interface with the Shaker K+ channel. The fold of agitoxin is homologous to the previously determined folds of scorpion venom toxins. However, agitoxin 2 differs significantly from the other channel blockers in the specificity of its interactions. This study was thus focused on a precise characterization of the surface residues at the face of the protein interacting with the Shaker K+ channel. The rigid toxin molecule can be used to estimate dimensions of the potassium channel. Surface-exposed residues, Arg24, Lys27, and Arg31 of the beta-sheet, have been identified from mutagenesis studies as functionally important for blocking the Shaker K+ channel. The sequential and spatial locations of Arg24 and Arg31 are not conserved among the homologous toxins. Knowledge on the details of the channel-binding sites of agitoxin 2 formed a basis for site-directed mutagenesis studies of the toxin and the K+ channel sequences. Observed interactions between mutated toxin and channel are being used to elucidate the channel structure and mechanisms of channel-toxin interactions. Solution structure of the potassium channel inhibitor agitoxin 2: caliper for probing channel geometry.,Krezel AM, Kasibhatla C, Hidalgo P, MacKinnon R, Wagner G Protein Sci. 1995 Aug;4(8):1478-89. PMID:8520473[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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