Activation of mouse splenic lymphocyte guanylate cyclase by calcium ion.
The guanosine 3',5'-cyclic monophosphate (cGMP) level in the mouse splenic lymphocytes was increased about 2- to 3-fold by concanavalin A. This increase was completely dependent on the presence of Ca2+ in the medium. Homogenates of mouse splenic lymphocytes contained significant guanylate cyclase [EC 4.6.1.2] activity in both the 105,000 X g (60 min) particulate and supernatant fractions and both fractions required Mn2+ for full activity. Calcium ion (3mM) activated soluble guanylate cyclase 3-fold at a relatively low concentration of Mn2+ (less than 1mM) but inhibited the particulate enzyme slightly at all Mn2+ concentrations tested. Concanavalin A itself did not stimulate either fraction of guanylate cyclase. Thus these results suggest that elevation of the cGMP level in lymphocytes by concanavalin A might be brought about by stimulation of Ca2+ uptake and activation of soluble guanylate cyclase by the latter.
D000818:Animals; D001402:B-Lymphocytes / Q000187:drug effects / Q000201:enzymology*; D002118:Calcium / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D006162:Guanylate Cyclase / Q000378:metabolism*; D007700:Kinetics; D008345:Manganese / Q000494:pharmacology; D051379:Mice
D008345:Manganese; D006162:Guanylate Cyclase; D002118:Calcium