Figure 3.

Galectin evolution. (a) Maximum-likelihood phylogeny of mammalian galectin CRD amino acid sequences inferred using RaxML with a Dayhoff matrix. Prototype galectins are numbered with red (o14: sheep ‘galectin-14’), chimera-type galectin with magenta, tandem-repeat-type galectins with black (F3 domains) and blue (F4 domains), galectin-related proteins (hs, HSPC159; gr, grifin) with orange. (b) Phylogenetic relationship among closely-related genes within the galectin-13-clade cluster [15]. Genes with predominant placental expression are highlighted in red. (c) Evidence for adaptive evolution of galectins in the anthropoid cluster is represented on the molecular backbone of galectin-16. Site-specific v values are indicated by the width of the molecular backbone and by a color spectrum [15]. ω values <, =, > 1 indicate purifying selection, neutral evolution, and positive selection, respectively; v values ranged between 0.2 and 2.2. Residues with greater v are wider and nearer the red range of the color spectrum. (d) The same color-coding shows that four conserved residues (53, 65, 72, 75) in the CRDs of cluster galectins are under strong purifying (i.e. negative) selection, others on the opposite side of the CRDs (55, 57, 63, 77) show more variability [15]. Figures adapted from [15], © National Academy of Sciences of the U.S.A.