G. Schreiber et al., TRANSTHYRETIN EXPRESSION EVOLVED MORE RECENTLY IN LIVER THAN IN BRAIN, Comparative biochemistry and physiology. B. Comparative biochemistry, 105(2), 1993, pp. 317-325
1. Transthyretin was found to be synthesized and secreted by choroid p
lexus from rats, echidnas, and lizards, but not toads. 2. Transthyreti
n was observed in blood from placental mammals, birds, and marsupials,
but not reptiles and monotremes. 3. The obtained data suggest that tr
ansthyretin synthesis by the liver evolved independently in the lineag
e leading to the placental mammals and marsupials and in that leading
to the birds. 4. It is proposed that transthyretin gene expression in
mammalian liver appeared about 200 million years later than its first
occurrence in the choroid plexus of the stem reptiles.