Molecular cloning and characterization of a type 3 iodothyronine deiodinase in the pine snake Pituophis deppei

► This is the first report of the cloning and expression of a reptilian D3 cDNA. ► Present results support the proposal that hepatic D3 in adult vertebrates plays a sentinel role in avoiding an inappropriate overload of exogenous T3 secondary to feeding in those species that devour thewhole prey. ► As in other D1s and D3s, the hinge region of PdD3 is rich in prolines, an observation that suggests that the presence of proline residues could be a specific feature of IRD-catalyzing enzymes.