Figure 1.

(a) The ribbon representation for monomeric Bos d 2. The eight antiparallel β-strands (A–H) forming a central barrel are shown as cyan arrows. The β-strand (I) outside the barrel is in green. The α-helix is in red and loops connecting different secondary structure elements are labelled L1 to L8. The black arrow shows the entrance to the ligand binding pocket (b) The monomers of 9 different lipocalin allergens which form symmetric homodimers are superimposed to observe the orientation of the second monomer. The superimposed monomers are in green and grey, blue and red colours are used for the second monomers.