1omb

SEQUENTIAL ASSIGNMENT AND STRUCTURE DETERMINATION OF SPIDER TOXIN OMEGA-AGA-IVB

spinqualitylabelsall models 1omb Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1omb is a 1 chain structure with sequence from Agelenopsis aperta. Full experimental information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: Solution NMR, 1 model Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function TX23B_AGEAP Antagonist of voltage-gated Cav2.1/CACNA1A (P-type) calcium channels. Paralyzes insect by blocking neuromuscular transmission. Publication Abstract from PubMed The solution structure of a peptide toxin isolated from funnel web spider venom, omega-Aga-IVB, was determined by 2D NMR methods. omega-Aga-IVB is a high-affinity specific blocker of P-type voltage-dependent calcium channels. Nearly all of the proton resonances of this 48-residue protein were assigned using conventional 2D homonuclear NMR experiments. The three-dimensional structure of the molecule was determined by simulated annealing. The distance and dihedral restraints used in the structure calculations were derived from NOESY and COSY-type experiments, respectively. Mass spectrometric analysis of omega-Aga-IVB suggests that the protein contains four disulfide bonds. In the absence of chemical data to identify the pattern of cysteine pairing, the disulfide bonds of the toxin are proposed from the NMR data and subsequent structural calculations. The structure of the toxin can be described as a three-stranded anti-parallel beta sheet connected by flexible loops. A striking feature of the structure is that the C-terminal 10 residues of this protein adopt random coil conformations. Several positively charged amino acid side chains are found localized on one face of the molecule, in close proximity to the C-terminal tail. This observation has led us to propose a speculative model of the toxins blockade mechanism. Sequential assignment and structure determination of spider toxin omega-Aga-IVB.,Yu H, Rosen MK, Saccomano NA, Phillips D, Volkmann RA, Schreiber SL Biochemistry. 1993 Dec 7;32(48):13123-9. PMID:8241166 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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