Characterization of the catalytic subunits of the different types of polycation-stimulated protein phosphatases.
Three polycation-stimulated (PCSH-, PCSM- and PCSL-) protein phosphatases are characterized by distinct specificities and regulatory properties. The properties of the catalytic subunits obtained from the 3 basic types of PCS phosphatases are apparently identical. The 35 kDa catalytic subunits are insensitive to inhibitor-1 and modulator protein and in contrast with the holoenzymes are less sensitive to stimulation by protamine, displaying a similar degree of stimulation and an identical concentration optimum; preincubation with polycations also results in a time-dependent deactivation. The phosphorylase phosphatase activity of the three catalytic subunits is stimulated to a similar extent by low but comparable concentrations of detergents, but not by metal ions. Upon limited proteolysis by trypsin the basal, but to a lesser extent the polycation-stimulated activity of the holoenzymes and the catalytic subunits is decreased.
Waelkens
E
E
Afdeling Biochemie, Faculteit Geneeskunde, Katholieke Universiteit te Leuven, Belgium.
Goris
J
J
Merlevede
W
W
D000818:Animals; D002412:Cations; D002846:Chromatography, Affinity; D002852:Chromatography, Ion Exchange; D046911:Macromolecular Substances; D008970:Molecular Weight; D009132:Muscles / Q000201:enzymology; D010749:Phosphoprotein Phosphatases / Q000302:isolation & purification / Q000378:metabolism*; D011479:Protamines / Q000494:pharmacology*; D011817:Rabbits; D014357:Trypsin / Q000378:metabolism
D002412:Cations; D046911:Macromolecular Substances; D011479:Protamines; D010749:Phosphoprotein Phosphatases; D014357:Trypsin