PHOSPHORYLATION OF ENDOGENOUS PROTEINS IN MYELIN OF RAT BRAIN

Abstract— The phosphorylation of endogenous proteins occurring in the myelin of rat brain was examined using the method of sodium dodecyl sulphate-polyacrylamide gel electrophoresis. Two myelin basic proteins and at least five more proteins were phosphorylated after incubation of myelin fraction in the presence of ATP + Mg²⁺. The apparent molecular weights of the proteins other than the myelin basic proteins were 120,000, 76,000, 60,000, 41,000 and 38,000, respectively. The proteins of mol wt 60,000. 41,000 and 38,000 were extracted by treatment with hydrochloric acid, whereas those of mol wt 120,000 and 76,000 were insoluble in hydrochloric acid and chloroform-methanol. Folch-Lees proteolipid protein was not found to be phosphorylated under the conditions studied. The endogenous phosphorylation of the proteins was not stimulated by adenosine 3',5'-monophosphate.