Phosphorylation of synaptic-membrane proteins from ox cerebral cortex in vitro. Partition of substrates and protein kinase activities with triton X-100

Synaptic-membrane fragments from ox cerebral cortex contain basal and cyclic AMP-stimulated protein kinase activity catalysing the phosphorylation of endogenous substrates. Extraction of membrane fragments with Triton X-100 solubilized less than 20% of the kinase activity and left the major part of the endogenous substrates in the insoluble fraction.