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Title: Structural Divergence in Vertebrate Phylogeny of a Duplicated Prototype Galectin

Prototype galectins, endogenously expressed animal lectins with a single carbohydrate recognition domain, are well-known regulators of tissue properties such as growth and adhesion. The earliest discovered and best studied of the prototype galectins is Galectin-1 (Gal-1). In the Gallus gallus (chicken) genome, Gal-1 is represented by two homologs: Gal-1A and Gal-1B, with distinct biochemical properties, tissue expression, and developmental functions. We investigated the origin of the Gal-1A/Gal-1B divergence to gain insight into when their developmental functions originated and how they could have contributed to vertebrate phenotypic evolution. Sequence alignment and phylogenetic tree construction showed that the Gal-1A/Gal-1B divergence can be traced back to the origin of the sauropsid lineage (consisting of extinct and extant reptiles and birds) although lineage-specific duplications also occurred in the amphibian and actinopterygian genomes. Gene synteny analysis showed that sauropsid gal-1b (the gene for Gal-1B) and its frog and actinopterygian gal-1 homologs share a similar chromosomal location, whereas sauropsid gal-1a has translocated to a new position. Surprisingly, we found that chicken Gal-1A, encoded by the translocated gal-1a, was more similar in its tertiary folding pattern than Gal-1B, encoded by the untranslocated gal-1b, to experimentally determined and predicted folds of nonsauropsid Gal-1s. This inference is consistent withmore » our finding of a lower proportion of conserved residues in sauropsid Gal-1Bs, and evidence for positive selection of sauropsid gal-1b, but not gal-1a genes. We propose that the duplication and structural divergence of Gal-1B away from Gal-1A led to specialization in both expression and function in the sauropsid lineage.« less
 [1] ;  [2] ;  [3] ;  [4]
  1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States), Life Sciences Division
  2. Univ. of California, Irvine, CA (United States). Department of Ecology and Evolutionary Biology
  3. Univ. College London, (United Kingdom). Department of Computer Science
  4. New York Medical College, Valhalla, New York, (United States). Department of Cell Biology and Anatomy
Publication Date:
OSTI Identifier:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Genome biology and evolution
Additional Journal Information:
Journal Volume: 6; Journal Issue: 10; Journal ID: ISSN 1759-6653
Society for Molecular Biology and Evolution
Research Org:
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
Sponsoring Org:
Country of Publication:
United States
60 APPLIED LIFE SCIENCES prototype galectin; galectin-1; sauropsids; protein fold; homology