Experimental Data Snapshot

  • Resolution: 1.90 Å
  • R-Value Work: 0.179 
  • R-Value Observed: 0.179 

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Crystal structures of guinea-pig, goat and bovine alpha-lactalbumin highlight the enhanced conformational flexibility of regions that are significant for its action in lactose synthase.

Pike, A.C.Brew, K.Acharya, K.R.

(1996) Structure 4: 691-703

  • DOI: https://doi.org/10.1016/s0969-2126(96)00075-5
  • Primary Citation of Related Structures:  
    1HFX, 1HFY, 1HFZ

  • PubMed Abstract: 

    The regulation of milk lactose biosynthesis is highly dependent on the action of a specifier protein, alpha-lactalbumin (LA). Together with a glycosyltransferase, LA forms the enzyme complex lactose synthase. LA promotes the binding of glucose to the complex and facilitates the biosynthesis of lactose. To gain further insight into the molecular basis of LA function in lactose synthase we have determined the structures of three species variants of LA. The crystal structures of guinea-pig, goat and a recombinant from of bovine LA have been determined using molecular replacement techniques. Overall, the structures are very similar and reflect their high degree of amino acid sequence identity (66-94%). Nonetheless, the structures show that a portion of the molecule (residues 105-110), known to be important for function, exhibits a variety of distinct conformers. This region lies adjacent to two residues (Phe31 and His32) that have been implicated in monosaccharide binding by lactose synthase and its conformation has significant effects on the environments of these functional groups. The crystal structures also demonstrate that residues currently implicated in LA's modulatory properties are located in a region of the structure that has relatively high thermal parameters and is therefore probably flexible in vivo. LA's proposed interaction site for the catalytic component of the lactose synthase complex is primarily located in the flexible C-terminal portion of the molecule. This general observation implies that conformational adjustments may be important for the formation and function of lactose synthase.

  • Organizational Affiliation

    School of Biology and Biochemistry, University of Bath, Claverton Down, UK.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
ALPHA-LACTALBUMIN123Cavia porcellusMutation(s): 0 
Find proteins for P00713 (Cavia porcellus)
Explore P00713 
Go to UniProtKB:  P00713
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP00713
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Query on CA

Download Ideal Coordinates CCD File 
Experimental Data & Validation

Experimental Data

  • Resolution: 1.90 Å
  • R-Value Work: 0.179 
  • R-Value Observed: 0.179 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 32.59α = 90
b = 64.87β = 90
c = 49γ = 90
Software Package:
Software NamePurpose
XENGENdata collection
X-PLORmodel building
XENGENdata reduction

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 1997-07-07
    Type: Initial release
  • Version 1.1: 2008-03-24
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2024-04-03
    Changes: Data collection, Database references, Derived calculations, Other, Refinement description