1kba

CRYSTAL STRUCTURE OF KAPPA-BUNGAROTOXIN AT 2.3-ANGSTROM RESOLUTION

spinqualitylabelsall models 1kba, resolution 2.30Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1kba is a 2 chain structure with sequence from Bunmu. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Related: 1nbt Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum Function [NXL1_BUNMU] Neurotoxin. Binds and inhibits nicotinic acetylcholine receptors. Compared to alpha-neurotoxins, kappa-neurotoxins bind more strongly to neuronal receptors, and less strongly to muscle receptors. 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 PubMed kappa-Neurotoxins display a very low affinity for neuromuscular receptors, but bind tightly to, and inhibit, nicotinic acetylcholine receptors in neuronal tissue such as the chick ciliary ganglia. In contrast, alpha-neurotoxins bind with high affinity and inhibit nicotinic acetylcholine receptors at the neuromuscular junction. The origin of this difference in specificity has been a long-studied question in the field. Here we report the first crystal structure of a kappa-neurotoxin, kappa-bungarotoxin. Unlike the NMR structure previously reported [Sutcliffe, M. J., Dobson, C. M., & Oswald, R. E. (1992) Biochemistry 31, 2962-2970], the present crystal structure more accurately defines the polypeptide fold and the nature of the interaction between subunits in the active dimer, which is a unique feature of the kappa-neurotoxins. The structure has been refined to R = 19.6% with X-ray diffraction data extending to a resolution of 2.3 A. There are two independent protein molecules (66 amino acid residues each) in the asymmetric unit that are arranged as a dimer with the two subunits related by a rotation of 178.6 degrees. Each subunit consists of three main-chain loops. Three of the five beta-strands of each subunit form an antiparallel beta-sheet which becomes an extended six-stranded antiparallel beta-sheet, by virtue of the approximate 2-fold symmetry of the dimer. The interactions at the dimer interface consist of six main-chain-main-chain hydrogen bonds, as well as three other hydrogen-bonding interactions involving side chains.(ABSTRACT TRUNCATED AT 250 WORDS) Crystal structure of kappa-bungarotoxin at 2.3-A resolution.,Dewan JC, Grant GA, Sacchettini JC Biochemistry. 1994 Nov 8;33(44):13147-54. PMID:7947721 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Bungarotoxin

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