Molecular convergence of infrared vision in snakes.

It has been discovered that the transient receptor potential ankyrin 1 (TRPA1) proteins of Boidae (boas), Pythonidae (pythons), and Crotalinae (pit vipers) are used to detect infrared radiation, but the molecular mechanism for detecting the infrared radiation is unknown. Here, relating the amino acid substitutions in their TRPA1 proteins and the functional differentiations, we propose that three parallel amino acid changes (L330M, Q391H, and S434T) are responsible for the development of infrared vision in the three groups of snakes. Protein modeling shows that the three amino acid changes alter the structures of the central region of their ankyrin repeats.