Molecular basis of hemoglobin adaptation in the high-flying bar-headed goose
Fig 4
Structural model showing bar-headed goose Hb in the deoxy state (PDB1hv4), along with locations of each of the three amino substitutions that occurred in the bar-headed goose lineage after divergence from the common ancestor of other Anser species.
The inset graphic shows the environment of the Val α63 residue. When valine replaces the ancestral alanine at this position, the larger volume of the side-chain causes minor steric clashes with two neighboring glycine residues, Gly α25 and Gly α59. The distances between non-hydrogen atoms (depicted by dotted lines) are given in Ǻ.