Multimolecular Forms of Pyruvate Kinase from Rat and Other Mammalian Tissues*

Imamura, Kiichi; Tanaka, Takehiko

doi:10.1093/oxfordjournals.jbchem.a129852

Cited by 350 publications

(148 citation statements)

References 0 publications

Supporting

Mentioning

139

Contrasting

Unclassified

Order By: Relevance

“…In fact, the activities of these protein phosphatases in heart muscle and brain (Table 1) are much higher than would be predicted from the rates of glycogenolysis, glycogen synthesis, fatty acid synthesis and cholesterol synthesis in these two tissues. Furthermore, pyruvate kinase is of the M-type in heart muscle and brain [40], an isoenzyme that is not phosphorylated by cyclic-AMP-dependent protein kinase [32]. Thus the protein phosphatases may regulate other cellular functions in these tissues.…”

Section: Physiological Roles Of Protein Phosphatases 1 2a and 2c In mentioning

confidence: 99%

The Protein Phosphatases Involved in Cellular Regulation. 6. Measurement of Type-1 and Type-2 Protein Phosphatases in Extracts of Mammalian Tissues; an Assessment of Their Physiological Roles

1983

View full text Add to dashboard Cite

Methods were developed for quantifying protein phosphatases-I, 2A, 2B and 2C in cell extracts, and these procedures were exploited to determine their tissue and subcellular distributions. In addition, the contribution of each enzyme to the total protein phosphatase activity in skeletal muscle and liver extracts towards nine proteins involved in the control of glycogen metabolism, glycolysis/gluconeogenesis, fatty acid synthesis and cholesterol synthesis was assessed.Each protein phosphatase was present at significant concentrations in skeletal muscle, heart muscle, liver, brain and adipose tissue, although the relative amounts differed considerably. In skeletal muscle, protein phosphatase-I was the major enzyme acting on phosphorylase, glycogen synthase and phosphorylase kinase (B-subunit), and thus was the major protein phosphatase responsible for the inactivation of glycogenolysis and stimulation of glycogen synthesis. This idea was reinforced by the observation that 50 ' %, of the protein phosphatase-I activity was associated with the protein-glycogen complex.In the liver, protein phosphatases-1, 2A and 2C each appear to play a role in the regulation of glycogen metabolism. Protein phosphatase-I accounted for a significant fraction of the total potential activity towards phosphorylase and glycogen synthase, and was the major phosphorylase kinase ([hubunit) phosphatase of this tissue. In addition, it was the only protein phosphatase present in the protein-glycogen complex. Protein phosphatase 2A was also a major phosphorylase phosphatase and glycogen synthase phosphatase in this tissue. Protein phosphatase 2C was a significant glycogen synthase phosphatase in the liver, but had negligible activity toward phosphorylase or phosphorylase kinase (p-subunit).In the absence of Ca2+, protein phosphatase 2A was the major phosphorylase kinase (a-subunit) phosphatase and the only inhibitor-1 phosphatase, in skeletal muscle or liver. In the presence of Ca2+, protein phosphatase 2B accounted for most of the activity towards these substrates.Protein phosphatase 2A was the major enzyme acting on L-pyruvate kinase, ATP-citrate lyase and acetyl-CoA carboxylase in rat liver, suggesting an important role in the regulation of glycolysis/gluconeogenesis and fatty acid synthesis. Protein phosphatase 2C was the major enzyme acting on hydroxymethylglutaryl-CoA (HMG-CoA) reductase and HMG-CoA reductase kinase, suggesting an important role in the regulation of cholesterol synthesis. However, the observation that 20% of the protein phosphatase-I in liver was associated with the microsomal fraction suggests that this enzyme may also be involved in regulating HMG-CoA reductase, which is tightly associated with microsomes.The activity of protein phosphatase-I in dilute skeletal muscle and liver extracts was just as sensitive to inhibitor-I and inhibitor-2 as the purified enzyme. In concentrated extracts, higher concentrations of the inhibitor proteins were required and the inhibition was time-dependent. The results explain previous report...

show abstract

Section: Physiological Roles Of Protein Phosphatases 1 2a and 2c In mentioning

confidence: 99%

The Protein Phosphatases Involved in Cellular Regulation. 6. Measurement of Type-1 and Type-2 Protein Phosphatases in Extracts of Mammalian Tissues; an Assessment of Their Physiological Roles

1983

View full text Add to dashboard Cite

show abstract

“…The degree of anemia varies widely, ranging from very mild or fully compensated anemia detected only in adulthood and, by chance, to life-threatening neonatal anemia and jaundice necessitating exchange transfusion and subsequent continuous transfusion therapy [3]. Human PK is present as four different isozymes (L, R, M 1 , M 2 ), the expression of which differs from one tissue to another [4]. Since R-PK is the only isozyme present in normal mature red cells, it has been suggested that the impairment of vital ATPdependent reactions in the R-PK deficiency leads to extravascular hemolysis.…”

Section: Introductionmentioning

confidence: 99%

Ineffective erythropoiesis in the spleen of a patient with pyruvate kinase deficiency

et al. 2003

View full text Add to dashboard Cite

In this study, possible adverse effects of pyruvate kinase (PK) deficiency on the maturation of erythroid progenitors were investigated. A 4-year-old Japanese girl with severe PK deficiency underwent splenectomy to reduce her need for blood transfusions. The spleen was examined a histologically, and the hematopoietic progenitors in the spleen were assayed to evaluate the extramedullary hematopoiesis of this PK-deficient subject. The number of hematopoietic progenitors including CFU-GM, BFU-E and CFU-GEMM in the spleen of the PK-deficient patient was much higher than those found in control spleens, indicating enhanced extramedullary hematopoiesis. TUNEL assay demonstrated apoptotic cells in the splenic red pulp of the PK-deficient patient. The expression of 7A6 antigen was detected in cells isolated from spleen and in cells cultured in vitro, but only in those cells that were positive for glycophorin A. These results provide evidence that the metabolic disturbances in PK deficiency affect not only the survival of red cells but also the maturation of erythroid progenitors, which results in premature cell death, i.e., apoptosis. Am. J. Hematol. 74:68-72, 2003.

show abstract

“…During ontogenesis, the αα embryonic isoform remains distributed in most adult cell types, whereas a transition towards specific isoforms occurs in two tissues with high and fluctuating energy requirements : αγ and γγ in the nervous system, αβ and ββ in striated muscles [3][4][5]. It is noteworthy that, among glycolytic enzymes having isoforms with preferential expression in nervous or striated muscle tissues [6][7][8], the enolase isoenzyme family is unique for the strict celltype specificity of the β and γ subunits.…”

Section: Introductionmentioning

confidence: 99%

Biochemical characterization of the mouse muscle-specific enolase: developmental changes in electrophoretic variants and selective binding to other proteins

Меркулова

Lucas

Jabet

et al. 1997

Biochemical Journal

View full text Add to dashboard Cite

The glycolytic enzyme enolase (EC 4.2.1.11) is active as dimers formed from three subunits encoded by different genes. The embryonic αα isoform remains distributed in many adult cell types, whereas a transition towards ββ and γγ isoforms occurs in striated muscle cells and neurons respectively. It is not understood why enolase exhibits tissue-specific isoforms with very close functional properties. We approached this problem by the purification of native ββ-enolase from mouse hindlimb muscles and by raising specific antibodies of high titre against this protein. These reagents have been useful in revealing a heterogeneity of the β-enolase subunit that changes with in i o and in itro maturation. A basic carboxypeptidase appears to be involved in generating an acidic β-enolase variant, and may regulate plasminogen binding by this subunit. We show for the

show abstract

Multimolecular Forms of Pyruvate Kinase from Rat and Other Mammalian Tissues*

Cited by 350 publications

References 0 publications

The Protein Phosphatases Involved in Cellular Regulation. 6. Measurement of Type-1 and Type-2 Protein Phosphatases in Extracts of Mammalian Tissues; an Assessment of Their Physiological Roles

The Protein Phosphatases Involved in Cellular Regulation. 6. Measurement of Type-1 and Type-2 Protein Phosphatases in Extracts of Mammalian Tissues; an Assessment of Their Physiological Roles

Ineffective erythropoiesis in the spleen of a patient with pyruvate kinase deficiency

Biochemical characterization of the mouse muscle-specific enolase: developmental changes in electrophoretic variants and selective binding to other proteins

Contact Info

Product

Resources

About