Proparathyroid hormone: biosynthesis by human parathyroid adenomas.

Biosynthesis of a precursor (proparathyroid hormone) to human parathyroid hormone was demonstrated during incubation of tissue from parathyroid adenomas. The proparathyroid hormone is labeled more rapidly than parathyroid hormone during incubation with amino acids labeled with carbon-14 and is progressively converted to the hormone. Apparent differences in the relative rate of conversion of precursor to hormone found in different tumors suggest that proparathyroid hormone may accumulate in some of the tumors and be secreted into the circulation.