Effect of prostaglandins on tyrosylprotein sulfotransferase activity in rat submandibular salivary glands.

1. Tyrosylprotein sulfotransferase (TPST) is a key enzyme in the processing of several secretory proteins, including those found in saliva. In this report, the effect of prostaglandins (PG) on TPST activity in submandibular salivary gland was investigated. 2. The results revealed that PGE2 exhibited TPST stimulatory activity with a 1.5-fold stimulation at 100 microM concentration and a half maximal stimulation at 50 microM. The PGE2 stimulation was accompanied by an increase in the affinity of TPST towards sulfate acceptor (Km 1.4 microM-->0.12 microM) with little change in Vmax. 3. The TPST activity was also stimulated by two other major prostaglandins of salivary glands, PGF2 alpha and 6-Keto-PGF 1 alpha, however to lesser extent, 22 and 23%, respectively. Arachidonic acid, an intermediate prostaglandin precursor, had no effect on TPST activity. 4. The results suggest that prostaglandins and in particular PGE2 may play a role in the regulation of TPST catalyzed secretory protein tyrosine sulfation in salivary glands.