Early Effects of Thyrotropin on Biosynthesis of Thyroglobulin in the Rat.

Abstract

The effects of a single dose of thyrotropin (TSH) on the incorporation in vivo of C-14 labeled amino acids into thyroid proteins of the rat were studied. Soluble thyroid proteins were analyzed by sucrose density-gradient ultra-centrifugation. TSH, injected 2 to 4 hr. before pulse-labeling, increased the total amount of C-14 in protein and accelerated the appearance of label in mature (19 S) thyroglobulin. When TSH was given within 1 hr. of labeling or 2 hr. afterward, total C-14 incorporation was unaffected, but the label appeared in 19 S thyroglobulin at the expense of label in 16 S protein, a presumed precursor of 19 S. TSH produces an early stimulation in vivo of several phases in the biosynthesis of thyroglobulin.