Studies on the phosphoproteins of brain. 3. Phosphorylserine sequences in brain phosphoprotein

In a previous paper it was reported that a phosphoprotein fraction isolated from brain was capable of accepting radioactive phosphate in a suitable phosphorylating system and that the phosphate incorporated could subsequently be isolated as phosphorylserine (Heald, 1961 a). It was later shown (Rose & Heald, 1961) that this phosphoprotein fraction was attacked, to a limited degree, by a specific phosphoprotein phosphatase isolated from brain.