title: Structure based studies of the adaptive diversification process of congerins.
abstract: The isoforms of a fish galectin, congerins I and II, have several features that make them suitable for a study of accelerated process of molecular diversification based on 3D structures: They have been generated by a gene duplication, and still maintain 47% amino acid sequence identity to each other. Their genes show very high K A: /K S: ratio, and are though to be components of fish defense system. The crystal systems for a high-resolution analysis are known for both proteins. A series of works with biochemistry, molecular biology, and X-ray crystallography techniques have suggested that the two proteins might have evolved under differential selection pressures. Congerin I appeared to be a stabilized version of galectin-1. Congerin II was shown to be adapted to a new carbohydrate-ligand. The 3D structures of the wild type and mutant proteins have revealed the probable cause and consequence of the selection pressure responsible for the diversification of congerins.
authors.affiliation: Department of Bioscience, Nagahama Institute of Bio-Science and Technology, 1266 Tamura, Nagahama, Siga, Japan. t_shirai@nagahama-i-bio-ac.jp
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Shirai
authors.forename: Clara
authors.initials: C
authors.lastname: Shionyu-Mitsuyama
authors.forename: Tomohisa
authors.initials: T
authors.lastname: Ogawa
authors.forename: Koji
authors.initials: K
authors.lastname: Muramoto
mesh_terms: D000222:Adaptation, Physiological; D001665:Binding Sites; D019143:Evolution, Molecular; D037161:Galectins / Q000737:chemistry / Q000235:genetics*; D008024:Ligands; D009154:Mutation; D017434:Protein Structure, Tertiary; D012641:Selection, Genetic; D040681:Structural Homology, Protein; D013329:Structure-Activity Relationship
chemical_list: D037161:Galectins; D008024:Ligands; C122080:congerin II protein, Conger eel; C074516:congerin protein, Conger myriaster