P2-purinergic agonists activate phospholipase C in a guanine nucleotide- and Ca2+-dependent manner in FRTL-5 thyroid cell membranes

AbstractVarious adenine nucleotides activated phospholipase C of FRTL-5 cell membranes in the following order of activity, ATPγS > ATP > AppNp > AppCp = ADP > MeSATP. This order was well consistent with that observed in intact cells. Such activation occurred only in the presence of appropriate concentrations of GTPγS and Ca2+, in a way similar to the norepinephrine-induced activation. NaF, a non-specific GTP-binding protein (G-protein) activator, also stimulated the enzyme. These adenine nucleotides, norepinephrine and NaF-induced activations were inhibited by GDPβS. We conclude that a G-protein is involved in the adenine nucleotides-induced activation of phospholipase C via P2-purinergic receptor in FRTL-5 cells