[Basal phosphorylation of synaptic membrane proteins in the presence of ATP and GTP].

A comparative study of endogenous ATP- and GTP-used basal protein phosphorylation in synaptic membranes from the rat brain cortex was carried out using the method of determination of total protein phosphorylation and autoradiography of proteins separated in PAGE. Under identical conditions 33P incorporation into proteins was shown to be appropriate in the presence of ATP as contrast to that in the case of GTP; in both cases the same proteins were phosphorylated. Inhibition of endogenous basal phosphorylation by alkali cations (K+, Na+, Li+) was more effective in the presence of GTP as compared to that with ATP. The differences between synaptic membrane protein kinases used by ATP and GTP are discussed.