1IE6

SOLUTION STRUCTURE OF IMPERATOXIN A


Experimental Data Snapshot

  • Method: SOLUTION NMR
  • Conformers Calculated: 100 
  • Conformers Submitted: 20 
  • Selection Criteria: The submitted conformer models are those with the lowest energy and the least restraint violations. 

wwPDB Validation   3D Report Full Report


This is version 1.3 of the entry. See complete history


Literature

Molecular basis of the high-affinity activation of type 1 ryanodine receptors by imperatoxin A.

Lee, C.W.Lee, E.H.Takeuchi, K.Takahashi, H.Shimada, I.Sato, K.Shin, S.Y.Kim, D.H.Kim, J.I.

(2004) Biochem J 377: 385-394

  • DOI: 10.1042/BJ20031192
  • Primary Citation of Related Structures:  
    1IE6

  • PubMed Abstract: 
  • Both imperatoxin A (IpTx(a)), a 33-residue peptide toxin from scorpion venom, and peptide A, derived from the II-III loop of dihydropyridine receptor (DHPR), interact specifically with the skeletal ryanodine receptor (RyR1), which is a Ca(2+)-release channel in the sarcoplasmic reticulum, but with considerably different affinities ...

    Both imperatoxin A (IpTx(a)), a 33-residue peptide toxin from scorpion venom, and peptide A, derived from the II-III loop of dihydropyridine receptor (DHPR), interact specifically with the skeletal ryanodine receptor (RyR1), which is a Ca(2+)-release channel in the sarcoplasmic reticulum, but with considerably different affinities. IpTx(a) activates RyR1 with nanomolar affinity, whereas peptide A activates RyR1 at micromolar concentrations. To investigate the molecular basis for high-affinity activation of RyR1 by IpTx(a), we have determined the NMR solution structure of IpTx(a), and identified its functional surface by using alanine-scanning analogues. A detailed comparison of the functional surface profiles for two peptide activators revealed that IpTx(a) exhibits a large functional surface area (approx. 1900 A(2), where 1 A=0.1 nm), based on a short double-stranded antiparallel beta-sheet structure, while peptide A bears a much smaller functional surface area (approx. 800 A(2)), with the five consecutive basic residues (Arg(681), Lys(682), Arg(683), Arg(684) and Lys(685)) being clustered at the C-terminal end of the alpha-helix. The functional surface of IpTx(a) is composed of six essential residues (Leu(7), Lys(22), Arg(23), Arg(24), Arg(31) and Arg(33)) and several other important residues (His(6), Lys(8), Arg(9), Lys(11), Lys(19), Lys(20), Gly(25), Thr(26), Asn(27) and Lys(30)), indicating that amino acid residues involved in RyR1 activation make up over the half of the toxin molecule with the exception of cysteine residues. Taken together, these results suggest that the site where peptide A binds to RyR1 belongs to a subset of macrosites capable of being occupied by IpTx(a), resulting in differing the affinity and the mode of activation.


    Organizational Affiliation

    Department of Life Science, Kwangju Institute of Science and Technology, Kwangju 500-712, South Korea.



Macromolecules
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Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
IMPERATOXIN AA33N/AMutation(s): 0 
UniProt
Find proteins for P59868 (Pandinus imperator)
Explore P59868 
Go to UniProtKB:  P59868
Entity Groups  
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UniProt GroupP59868
Protein Feature View
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: SOLUTION NMR
  • Conformers Calculated: 100 
  • Conformers Submitted: 20 
  • Selection Criteria: The submitted conformer models are those with the lowest energy and the least restraint violations. 

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2003-06-10
    Type: Initial release
  • Version 1.1: 2008-04-27
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2022-02-23
    Changes: Data collection, Database references, Derived calculations