Ontogenetic changes in protein dephosphorylating activity of the cytosolic compartment of rat erythrocytes.
Total casein phosphatase activity of erythrocytes from one-month-old rats was separated by DEAE-cellulose chromatography into three peaks--E1, E2 and E3--and only into two peaks--E1 and E3--when the erythrocyte donors were six- and 12-month-old rats. The activity of E1 (Mr 330 K) decreased continuously in erythrocytes during the first year of postnatal life. E2 (Mr 230 K) also decreased and completely disappeared from the cells of 12-month-old rats. E3 (Mr 180 K) was the dominant molecular form in the cytosol of erythrocytes during the first year of life. It decreased only up to six months of life. In this form E3 seems to be cooperative with respect to the substrate and to inhibitor molecules. The decrease of its kinetic parameters (Vmax and K0.55) was also found during postnatal ontogenesis. E3 isolated from erythrocytes of older rats (6 and 12 months) was more susceptible to inhibitory effect of pyrophosphate and to the change of ionic strength of eluting buffer than the enzyme from one-month-old rats. 0.2 mol.1(-1) NaCl lowered Mr of E3 phosphatase from 180 K to 128 K only in older rats.
D000375:Aging; D000818:Animals; D003600:Cytosol / Q000201:enzymology; D004905:Erythrocyte Aging; D004912:Erythrocytes / Q000201:enzymology*; D007527:Isoenzymes / Q000097:blood / Q000302:isolation & purification; D007700:Kinetics; D010749:Phosphoprotein Phosphatases / Q000097:blood* / Q000302:isolation & purification; D051381:Rats; D011919:Rats, Inbred Strains; D012156:Reticulocytes / Q000201:enzymology
D007527:Isoenzymes; D010749:Phosphoprotein Phosphatases