The X-ray crystal structure of eta-crystallin

Experimental Data Snapshot

  • Resolution: 2.40 Å
  • R-Value Free: 0.254 
  • R-Value Work: 0.180 
  • R-Value Observed: 0.184 

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Crystal Structure of Eta-Crystallin: Adaptation of a Class 1 Aldehyde Dehydrogenase for a New Role in the Eye Lens

Bateman, O.A.Purkiss, A.G.Van Montfort, R.Slingsby, C.Graham, C.Wistow, G.

(2003) Biochemistry 42: 4349

  • DOI: https://doi.org/10.1021/bi027367w
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    Eta-crystallin is a retinal dehydrogenase that has acquired a role as a structural protein in the eye lens of elephant shrews, members of an ancient order of mammals. While it retains some activity toward retinal, which is oxidized to retinoic acid, the protein has acquired a number of specific sequence changes that have presumably been selected to enhance the lens role. The crystal structure of eta-crystallin, in common with class 1 and 2 ALDHs, is a dimer of dimers. It has a better-defined NAD binding site than those of related mammalian ALDH1 enzymes with the cofactor bound in the "hydride transfer" position in all four monomers with small differences about the dimer dyads. Although the active site is well conserved, the substrate-binding site is larger in eta-crystallin, and there are some mutations to the substrate access tunnel that might affect binding or release of substrate and product. It is possible that eta-crystallin has lost flexibility to improve its role in the lens. Enhanced binding of cofactor could enable it to act as a UV/blue light filter in the lens, improving visual acuity. The structure not only gives a view of a "natural mutant" of ALDH1 illustrating the adaptive conflict that can arise in multifunctional proteins, but also provides a well-ordered NAD binding site structure for this class of enzymes with important roles in development and health.

  • Organizational Affiliation

    Birkbeck College, School of Crystallography, Malet Street, London WC1E 7HX, UK.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
A, B, C, D
501Elephantulus edwardiiMutation(s): 0 
Gene Names: ALDH1
Find proteins for Q28399 (Elephantulus edwardii)
Explore Q28399 
Go to UniProtKB:  Q28399
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ28399
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.40 Å
  • R-Value Free: 0.254 
  • R-Value Work: 0.180 
  • R-Value Observed: 0.184 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 80.869α = 90
b = 136.407β = 102.62
c = 84.988γ = 90
Software Package:
Software NamePurpose
MOSFLMdata reduction
SCALAdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2003-04-17
    Type: Initial release
  • Version 1.1: 2011-05-08
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance