2fqc
From Proteopedia
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Solution structure of conotoxin pl14a
Overview
Using assay-directed fractionation of the venom from the vermivorous cone, snail Conus planorbis, we isolated a new conotoxin, designated pl14a, with, potent activity at both nicotinic acetylcholine receptors and a, voltage-gated potassium channel subtype. pl14a contains 25 amino acid, residues with an amidated C-terminus, an elongated N-terminal tail (six, residues), and two disulfide bonds (1-3, 2-4 connectivity) in a novel, framework distinct from other conotoxins. The peptide was chemically, synthesized, and its three-dimensional structure was demonstrated to be, well-defined, with an alpha-helix and two 3(10)-helices present. Analysis, of a cDNA clone encoding the prepropeptide precursor of pl14a revealed a, novel signal sequence, indicating that pl14a belongs to a new gene, superfamily, the J-conotoxin superfamily. Five additional peptides in the, J-superfamily were identified. Intracranial injection of pl14a in mice, elicited excitatory symptoms that included shaking, rapid circling, barrel, rolling, and seizures. Using the oocyte heterologous expression system, pl14a was shown to inhibit both a K+ channel subtype (Kv1.6, IC50 = 1.59, microM) and neuronal (IC50 = 8.7 microM for alpha3beta4) and neuromuscular, (IC50 = 0.54 microM for alpha1beta1 epsilondelta) subtypes of the, nicotinic acetylcholine receptor (nAChR). Similarities in sequence and, structure are apparent between the middle loop of pl14a and the second, loop of a number of alpha-conotoxins. This is the first conotoxin shown to, affect the activity of both voltage-gated and ligand-gated ion channels.
About this Structure
2FQC is a Protein complex structure of sequences from [1] with NH2 as ligand. Full crystallographic information is available from OCA.
Reference
A novel conotoxin inhibitor of Kv1.6 channel and nAChR subtypes defines a new superfamily of conotoxins., Imperial JS, Bansal PS, Alewood PF, Daly NL, Craik DJ, Sporning A, Terlau H, Lopez-Vera E, Bandyopadhyay PK, Olivera BM, Biochemistry. 2006 Jul 11;45(27):8331-40. PMID:16819832
Page seeded by OCA on Wed Nov 21 10:42:07 2007
