Phosvitin kinase from brain: activation by ions and subcellular distribution.

Protein kinases (Rabinowitz, 1962) catalysing the transfer of the terminal phosphate of ATP to phosvitin, casein and possibly other phosphoproteins have been found in mammalian liver (Burnett & Kennedy, 1954), mammary gland (Sundararajan, Sampath-Kumar & Sarma, 1960), erythrocyte membranes (Judah, Ahmed & McLean, 1962) and brain (Rabinowitz & Lipmann, 1960). The following study of a protein kinase from cerebral cortex was prompted by a number of observations suggesting that a phosphoprotein may be involved in the transport of cations across the cell membrane. For example, on the application of electrical pulses to slices of cerebral cortex in vitro, the incorporation of added [32P]phosphate into a tissue phosphoprotein increases concomitantly with