EVIDENCE OF IN VIVO PHOSPHORYLATION OF ERYTHROCYTE AND LIVER PYRUVATE KINASES

SHINYA FUJII, KOJI NAKASHIMA, TOSHIO KANEKO
1981 Biomedical research  
Rat red cells and liver were obtained 4 hr after intravenous injection of ortho[32P]phosphate. Erythrocyte pyruvate kinase (PK; EC 2.7.1.40) and L-type PK were recovered by the double antibody technique and applied to SDS-polyacrylamide gel electrophoresis. Incorporation of "P into erythrocyte PK and L-type PK was detected on autoradiograms of the electrophoresis corresponding to the L' and L subunits, respectively. The results demonstrated directly in viva phosphorylation of rat erythrocyte
more » ... rat erythrocyte and L-type PKs. Rat and human erythrocyte PKs of the partially purified samples were phosphorylated using [T-32P]ATP. These phosphorylated PKs labelled with "P were incubated with MgCl2, resulting in the dephosphorylation and reactivation ofthe PKs, which indicate in viva dephosphorylation by the endogenous phosphoprotein phosphatase. Under the identical experimental conditions, samples freshly prepared from human red cells and human liver incubated with MgCl, resulted in the elevation of PK activity, indicating that human erythrocyte and L-type PKs are dephosphorylated by endogenous phosphatase in the presence of MgCl2. These results present indirect evidence that human erythrocyte a.nd L-type PKs are regulated in viva by the phosphorylation-dephosphorylation process. KEY WORDS phosphorylation / erythrocyte pyruvate kinase / L-type pyruvate kinase
doi:10.2220/biomedres.2.316 fatcat:ea2giogopjdbrfnzsvuoyefo6u