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G Vereb

Publications and source records attributed to G Vereb.

46 records · Page 3Linked to original sources
PubMed1978

Role of SH groups in the activity of pig phosphorylase b isoenzymes.

The reaction of phosphorylases from rabbit skeletal muscle, pig skeletal muscle and pig heart with DTNB and the effects of AMP and glucose-6-phosphate on the above reaction were examined and compared. The SH groups of pig heart-specific phosphorylase b were found to be the same as those of rabbit skeletal muscle. Pig skeletal muscle phosphorylase b differed from the foregoing enzymes in that its slowly reacting SH groups played a minor role in the catalytic activity and AMP and glucose-6-phosphate affected neither the DTNB reaction nor the small decrease of activity during the reaction.

Animals↗
PubMed1977

Studies on heart isophosphorylases by means of immunotitration.

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.

Animals↗
PubMed1976

Thiophosphate-activated phosphorylase kinase as a probe in the regulation of phosphorylase phosphatase.

Rabbit muscle nonactivated phosphorylase kinase (EC 2.7.1.38) is converted to thiophosphate-activated phosphorylase kinase by cyclic AMP dependent protein kinase, Mg2+ and ATP-gamma-S/adenosine-5'-O-(s-thiotriphosphate)/. The formation of thiophosphate-activated phosphorylase kinase wal also observed in the protein-glycogen complex from skeletal muscle. This new form of kinase is resistant to the action of phosphatase and behaves as a competitive inhibitor in the dephosphorylation of phosphorylase alpha by phosphorylase phosphatase (Ki = 0.04 mg per ml). The fact that the inhibitory effect of thiophosphate-activated phosphorylase kinase is 3 times higher than in the case of nonactivated kinase, may explain the transient inhibition of phosphorylase phosphatase in the protein-glycogen complex. The use of activated (phosphorylated) phosphorylase kinase supports this assumption since it causes a delay in the dephosphorylation of phosphorylase alpha, i.e. the conversion of phosphorylase alpha into beta could start only after the dephosphorylation of activated phosphorylase kinase.

Adenosine Triphosphate↗
PubMed1975

Properties of skeletal muscle phosphorylase-protein complexes.

Frontal gel filtration studies on muscle extract and mixture of purified enzymes have verified the existence of a protein-complex between phosphorylase (alpha-1,4-glucan: orthophosphate glycosyltransferase EC 2.4.1.1.) and phosphorylase kinase. The complex has an apparent molecular weight of 750 000 daltons. The complex formation depends on the protein concentration and the presence of Ca2+. Removal of Ca2+ with EGTA results in the dissociation of the complex. A regulatory role may be attributed to Ca2+ since the concentration of free Ca2+ changes in skeletal muscle through the effect of hormonal or electrical stimulation. Strong association was also detected between phosphorylase kinase and phosphorylase phosphatase. The transient inhibition of phosphorylase phosphatase can be explained by this interaction.

Animals↗
PubMedDate not supplied

Plasma-membrane-bound macromolecules are dynamically aggregated to form non-random codistribution patterns of selected functional elements. Do pattern recognition processes govern antigen presentation and intercellular interactions?

Molecular recognition processes between cell surface elements are discussed with special reference to cell surface pattern formation of membrane-bound integral proteins. The existence, as detected by flow cytometric resonance energy transfer (Appendix), and significance of cell surface patterns involving the interleukin-2 receptor, the T-cell receptor-CD3 system, the intercellular adhesion molecule ICAM-1, and the major histocompatibility complex class I and class II molecules in the plasma membrane of lymphocytes are described. The modulation of antigen presentation by transmembrane potential changes is discussed, and a general role of transmembrane potential changes, and therefore of ion channel activities, adduced as one of the major regulatory mechanisms of cell-cell communication. A general role in the mediation and regulation of intercellular interactions is suggested for cell-surface macromolecular patterns. The dynamic pattern of protein and lipid molecules in the plasma membrane is generated by the genetic code, but has a remarkable flexibility and may be one of the major instruments of accommodation and recognition processes at the cellular level.

Animals↗