Experimental Data Snapshot

  • Resolution: 1.10 Å
  • R-Value Free: 0.157 
  • R-Value Work: 0.147 
  • R-Value Observed: 0.147 

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This is version 1.3 of the entry. See complete history


Crystal structure at 1.1 A resolution of alpha-conotoxin PnIB: comparison with alpha-conotoxins PnIA and GI.

Hu, S.H.Gehrmann, J.Alewood, P.F.Craik, D.J.Martin, J.L.

(1997) Biochemistry 36: 11323-11330

  • DOI: https://doi.org/10.1021/bi9713052
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    Conotoxins are small, cysteine-rich peptides isolated from the venom of Conus spp. of predatory marine snails, which selectively target specific receptors and ion channels critical to the functioning of the neuromuscular system. alpha-Conotoxins PnIA and PnIB are both 16-residue peptides (differing in sequence at only two positions) isolated from the molluscivorous snail Conus pennaceus. In contrast to the muscle-selective alpha-conotoxin GI from Conus geographus, PnIA and PnIB block the neuronal nicotinic acetylcholine receptor (nAChR). Here, we describe the crystal structure of PnIB, solved at a resolution of 1.1 A and phased using the Shake-and-Bake direct methods program. PnIB crystals are orthorhombic and belong to the space group P212121 with the following unit cell dimensions: a = 14.6 A, b = 26.1 A, and c = 29.2 A. The final refined structure of alpha-conotoxin PnIB includes all 16 residues plus 23 solvent molecules and has an overall R-factor of 14.7% (R-free of 15.9%). The crystal structures of the alpha-conotoxins PnIB and PnIA are solved from different crystal forms, with different solvent contents. Comparison of the structures reveals them to be very similar, showing that the unique backbone and disulfide architecture is not strongly influenced by crystal lattice constraints or solvent interactions. This finding supports the notion that this structural scaffold is a rigid support for the presentation of important functional groups. The structures of PnIB and PnIA differ in their shape and surface charge distribution from that of GI.

  • Organizational Affiliation

    Centre for Drug Design and Development, University of Queensland, Brisbane, QLD 4072 Australia.


Find similar proteins by:  Sequence   |   3D Structure  

Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
ALPHA-CONOTOXIN PNIB17Conus pennaceusMutation(s): 0 
Membrane Entity: Yes 
Find proteins for P50985 (Conus pennaceus)
Explore P50985 
Go to UniProtKB:  P50985
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP50985
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 1.10 Å
  • R-Value Free: 0.157 
  • R-Value Work: 0.147 
  • R-Value Observed: 0.147 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 14.6α = 90
b = 26.1β = 90
c = 29.2γ = 90
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling
SHAKE-N-BAKEmodel building
X-PLORmodel building

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 1998-05-20
    Type: Initial release
  • Version 1.1: 2008-03-04
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2015-06-10
    Changes: Source and taxonomy