Glutamic acid decarboxylase in Rhodotorula glutinis.

1. The metabolism of 131I-labelled thyroglobulin from four mammalian species has been studied. 2. The rat, dog and monkey rapidly metabolize the homologous protein, with the formation of iodide, iodotyrosines and thyroxine. Rabbit thyroglobulin disappears slowly from the plasma of the rabbit after intravenous injection, and no metabolites have so far been detected in the blood. 3. The development of immune reactions to foreign thyroglobulins has been observed in all the species. 4. Heterologous thyroid protein is, in general, cleared from the plasma of non-immune animals of all four species without the appearance in the plasma of significant amounts of simple metabolites. This is not so, however, when monkey thyroglobulin is injected into rats and vice versa, for rapid metabolism takes place and thyroxine appears in the plasma. REFERENCES