Structural highlights
Function[CO16B_CONST] Omega-conotoxins act at presynaptic membranes, they bind and block voltage-gated calcium channels (Cav). This toxin blocks N-, P- and Q-type calcium channels. Publication Abstract from PubMedThe omega-conotoxins are a set of structurally related peptides that have a wide range of specificities for different subtypes of the voltage-sensitive calcium channel (VSCC). To understand their VSCC subtype differentiation we studied the structure of two naturally occurring omega-conotoxins, MVIIA (specific to N-type) and SVIB (specific to P/Q-type) and a synthetic hybrid, SNX-202, which has altered specificities to both VSCC subtypes. The secondary structures of the three peptides are almost identical, consisting of a triple-stranded beta-sheet and several turns. A comparison of NMR data emphasizes the structural similarities between the peptides and highlights some minor structural differences. In the three-dimensional structures of SVIB and MVIIA these are manifested as orientational differences between two key loops. The structural rigidity of MVIIA was also examined. H alpha shifts are similar in a range of solvents, indicating that there are no solvent-induced changes in structure. The omega-conotoxins form a consensus structure despite differences in sequence and VSCC subtype specificity. This indicates that the omega-conotoxin macrosites for the N/P/Q-subfamily of VSCCs are related, with specificity for receptor targets being conferred by the positions of functional side-chains on the surface of the peptides. A consensus structure for omega-conotoxins with different selectivities for voltage-sensitive calcium channel subtypes: comparison of MVIIA, SVIB and SNX-202.,Nielsen KJ, Thomas L, Lewis RJ, Alewood PF, Craik DJ J Mol Biol. 1996 Oct 25;263(2):297-310. PMID:8913308[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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