1agg
From Proteopedia
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THE SOLUTION STRUCTURE OF OMEGA-AGA-IVB, A P-TYPE CALCIUM CHANNEL ANTAGONIST FROM THE VENOM OF AGELENOPSIS APERTA
Overview
The 48 amino acid peptides omega-Aga-IVA and omega-Aga-IVB are the first, agents known to specifically block P-type calcium channels in mammalian, brain, thus complementing the existing suite of pharmacological tools used, for characterizing calcium channels. These peptides provide a new set of, probes for studies aimed at elucidating the structural basis underlying, the subtype specificity of calcium channel antagonists. We used 288, NMR-derived constraints in a protocol combining distance geometry and, molecular dynamics employing the program DGII, followed by energy, minimization with Discover to derive the three-dimensional structure of, omega-Aga-IVB. The toxin consists of a well-defined core region, comprising seven solvent-shielded residues and a well-defined, triple-stranded beta-sheet. Four loop regions have average backbone rms, deviations between 0.38 and 1.31 A, two of which are well-defined type-II, beta-turns. Other structural features include disordered C- and N-termini, and several conserved basic amino acids that are clustered on one face of, the molecule. The reported structure suggests a possible surface for, interaction with the channel. This surface contains amino acids that are, identical to those of another known P-type calcium channel antagonist, omega-Aga-IVA, and is rich in basic residues that may have a role in, binding to the anionic sites in the extracellular regions of the calcium, channel.
About this Structure
1AGG is a Single protein structure of sequence from Agelenopsis aperta. Full crystallographic information is available from OCA.
Reference
The solution structure of omega-Aga-IVB, a P-type calcium channel antagonist from venom of the funnel web spider, Agelenopsis aperta., Reily MD, Thanabal V, Adams ME, J Biomol NMR. 1995 Feb;5(2):122-32. PMID:7703698
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