FIGURE 1.

Lipocalin functions mapped on the dendrogram of Lipocalin evolutionary history (Diez-Hermano et al.) where major monophyletic clades are shown. Physiological functions identified are classified into homeostatic (blue tones) and defensive (red tones). Functions defined at the molecular level (green tones) also include antioxidant (purple). The first appearance of these molecular functions in the evolutionary path of chordate Lipocalin are indicated in the tree using the same colour code. Antioxidant, enzymatic activity, and membrane modulation are ancestral functions. The current knowledge places transport/signalling at the divergence of RBP4 and PGDS-related radiation. In contrast, proteolysis regulation appeared later in evolution.