Action of thyrotropin on phosphate incorporation into thyroid proteins in vitro.

It is now well established that cAMP is the intracellular mediator of many effects of thyrotropin on the thyroid. Greengard has postulated that all the effects of cAMP inside the cell are secondary to the phosphorylation of proteins by cAMP activated protein kinase(s). The purpose of our work is to define, in an intact cell system, the nature of the thyroid proteins, the phosphorylation of which is stimulated by cAMP and TSH.