The secretion of parathormone and glycosylated proteins by parathyroid cells in culture

The secretion of radioactive peptides by dispersed porcine parathyroid cells incubated with ³H]- or ¹⁴C]amino acids, ³H]glucosamine and ³H]mannose was analyzed. After incubation, the culture medium contained radioactive parathormone, as expected, and two radioactive glycopeptides: SP I and SP II. SP I appears to be identical with $\text{parathyroid}\text{secretory}\text{protein}$, heretofore not recognized as a glycoprotein. SP II has not been previously identified. SP I, but not SP II or parathormone, was adsorbed by Concanavalin A possibly reflecting a high mannose content of this molecule. Raising the concentration of calcium in the medium suppressed the secretion of radioactive parathormone and SP I in a similar fashion but did not affect the secretion of SP II. Our results suggest that SP I may play a fundamental role in parathyroid synthetic or secretory processes.