Adaptive evolution of conger eel galectins

Abstract

Two galectins isolated from the skin mucus of conger eel (Conger myriaster), named congerins I and II, are dimers composed of two identical subunits of 136 and 135 amino acid residues, respectively. They belong to the proto-type galectins and showed 48% sequence identity and different thermal stabilities and different sugar binding. The molecular evolutionary analyses and X-ray crystallography analyses of congerins I and II reveal that they have evolved in an accelerating and adaptive manner to the emergence of a new structure including domain-swapping manner and a unique new ligand-binding site. In this review, we summarize and discuss the structure-properties/function relationships and the molecular evolution of fish galectins.