J. Biol. Chem., Vol. 255, Issue 5, 2026-2029, Mar, 1980
Prostaglandins increase GTP hydrolysis by membranes from human mononuclear cells
AJ Bitonti, J Moss, NN Tandon and M Vaughan
Both adenylate cyclase and GTPase activities in human mononuclear cell
membranes were increased by prostaglandins. Adenylate cyclase activity,
however, was enhanced by much lower concentrations of PGE1 (prostaglandin
E1) than were required to increase GTPase. PGE2, PGA1, PGB1, and PGF1 alpha
also stimulated GTPase activity. These same prostaglandins, with the
notable exception of PGF1 alpha, increased adenylate cyclase activity (PGE2
greater than PGA1 greater than or equal to PGB1). Isoproterenol, 100
microM, doubled adenylate cyclase without altering GTPase activity.
Choleragen activated adenylate cyclase in mononuclear cell membranes but
had no effect on GTPase activity whether or not PGE1 was present.
Mononuclear cells were separated into adherent and nonadherent populations
by two different methods to examine the possibility that the
prostaglandin-stimulated GTPase was confined to a specific type of
mononuclear cell. Adenylate cyclase in membranes from both adherent and
nonadherent cells was activated by PGE1, but neither PGE1 nor choleragen
altered GTPase activity in these preparations. It appears that, although
several prostaglandins can increase GTPase activity in mononuclear cell
membranes, the increase in GTPase activity is not consistently associated
with activation of adenylate cyclase by prostaglandins.
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