Showing papers by "Pál Gergely published in 1977"

Regulation of phosphorylase-phosphatase from skeletal muscle by phosphorylation of a regulator protein.

Abstract: The inhibitory effect of a heat-stable regulator protein from skeletal muscle on the activity of phosphorylase-phosphatase (EC 3.1.3.17) was studied. The regulator protein was shown to be both phosphorylated and dephosphorylated in vivo as well as in vitro. The incorporation of phosphate into the regulator protein increased, while dephosphorylation decreased the ability of the protein to inhibit phosphatase activity. Our results suggest that the reversible phosphorylation of the regulator protein plays an essential role in the regulation of phosphorylase-phosphatase activity.

Studies on heart isophosphorylases by means of immunotitration

Abstract: Anti-phosphorylase produced in cocks against phosphorylase from rabbit skeletal muscle inhibits phosphorylases isolated from mammalian heart and skeletal muscle to different degrees. On the basis of the differential inhibition observed an immunotitration method was developed to determine isophosphorylases in crude heart extracts. It was found that the ratio of isophosphorylases is different for every mammalian species investigated and characteristic for the given species.

Antibody-dependent cellular cytotoxic activity in patients with Hodgkin disease.

Abstract: Antibody-dependent cellular cytotoxic activity (ADCC) of twenty-one previously treated patients (stage I--IV) with Hodgkin disease (HD) and eleven healthy controls was studied using specific antibody coated chicken erythrocyte target cells. Cytotoxicity was found to be normal in seven, slightly increased in ten, and considerably increased in four patients. No correlation with the absolute number of lymphocytes, the percentage of spontaneous rosette-forming cells and immunoglobulin bearing lymphocytes was noted. Nor did ADCC correlate with age and clinical or histological classification.

Role of tetramer in equilibrium dimer equilibrium in the dephosphorylation and activity of phosphorylase a.

Abstract: Skeletal muscle phosphorylase a exists as a tetramer or a dimer depending upon the temperature and protein concentration. The rate of dephosphorylation by phosphorylase phosphatase is very low at 18 degrees C where phosphorylase a exists as a tetramer. Caffeine markedly increases the rate of dephosphorylation of tetrameric phosphorylase a at 18 degrees C but has no effect on the dephosphorylation of the dimeric form. Caffeine also enhances the enzymic activity of phosphorylase a at 18 degrees C. The results presented here indicate that caffeine can shift the tetramer in equilibrium dimer equilibrium toward the dimeric form at 18 degrees C. This conclusion in supported by sedimentation analyses.

Antibody-dependent cellular cytotoxicity in systemic lupus erythematosus.

Abstract: Antibody-dependent cellular cytotoxicity of peripheral blood mononuclear cells from fourty-six patients with systemic lupus erythematosus was found to be reduced in two independent test systems. The percentage decrease in cytotoxicity was similar in the tests with allogeneic and xenogeneic targets and it was related to the activity of systemic lupus erythematosus.