Crystal structure of the dog lipocalin allergen Can f 2: implications for cross-reactivity to the cat allergen Fel d 4

J Mol Biol. 2010 Aug 6;401(1):68-83. doi: 10.1016/j.jmb.2010.05.043. Epub 2010 May 26.


The dog lipocalin allergen Can f 2 is an important cause of allergic sensitization in humans worldwide. Here, the first crystal structure of recombinant rCan f 2 at 1.45 A resolution displays a classical lipocalin fold with a conserved Gly-Xaa-Trp motif, in which Trp19 stabilizes the overall topology of the monomeric rCan f 2. Phe38 and Tyr84 localized on the L1 and L5 loops, respectively, control access to the highly hydrophobic calyx. Although the rCan f 2 calyx is nearly identical with the aero-allergens MUP1, Equ c 1 and A2U from mouse, horse and rat, respectively, no IgE cross-reactivity was found using sera from five mono-sensitized subjects. However, clear IgE cross-reactivity was demonstrated between Can f 2 and the cat allergen Fel d 4, although they share less than 22% sequence identity. This suggests a role for these allergens in co-sensitization between cat- and dog-allergic patients.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Allergens / chemistry*
  • Allergens / immunology*
  • Amino Acid Sequence
  • Animals
  • Antibody Specificity
  • Antigens, Plant
  • Cats
  • Cross Reactions
  • Crystallization
  • Crystallography, X-Ray
  • Dogs
  • Female
  • Glycoproteins / chemistry*
  • Glycoproteins / immunology*
  • Humans
  • Lipocalins / chemistry*
  • Lipocalins / immunology
  • Mice
  • Mice, Inbred BALB C
  • Models, Molecular
  • Molecular Sequence Data
  • Protein Conformation
  • Sequence Homology, Amino Acid


  • Allergens
  • Antigens, Plant
  • Fel d 4 allergen, Felis domesticus
  • Glycoproteins
  • Lipocalins
  • allergen Can f 2

Associated data

  • PDB/3L4R