Pancreatic islets contain the M2 isoenzyme of pyruvate kinase its phosphorylation has no effect on enzyme activity

@article{MacDonald2004PancreaticIC,
  title={Pancreatic islets contain the M2 isoenzyme of pyruvate kinase its phosphorylation has no effect on enzyme activity},
  author={Michael J. MacDonald and Cheng-Min Chang},
  journal={Molecular and Cellular Biochemistry},
  year={2004},
  volume={68},
  pages={115-120}
}
To determine which of the major isoenzymes of pyruvate kinase pancreatic islet pyruvate kinase most resembled, it was compared to pyruvate kinase from other tissues in kinetic and immunologic studies. The pattern of activation by fructose bisphosphate and the patterns of inhibition by alanine and phenylalanine were most similar to those of the M2 isoenzyme from kidney and were dissimilar to those of the isoenzymes from skeletal muscle (type M1) and liver (type L). The islet pyruvate kinase was… Expand
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References

SHOWING 1-10 OF 19 REFERENCES
Hepatic pyruvate kinase. Quantitative measurements of phosphorylation in vitro and in the isolated rat hepatocyte.
TLDR
It is suggested that some of the subunits of hepatic pyruvate kinase are modified such that they lose the capacity to be phosphorylated and may occur in the intact cell and are not an artifact of purification. Expand
High content of mitochondrial glycerol-3-phosphate dehydrogenase in pancreatic islets and its inhibition by diazoxide.
TLDR
The results of this study are compatible with the hypothesis that the mitochondrial glycerol phosphate dehydrogenase has a key role in stimulus-secretion coupling in the pancreatic beta cell during glucose-induced insulin release. Expand
Purification and characterization of pig kidney pyruvate kinase (type A).
TLDR
The amino acid compositions of pig kidney and pig muscle pyruvate kinases were very similar and differed clearly from that of pig liver pyruVate kinase. Expand
Calmodulin-activated protein kinase activity in rat pancreatic islet cell membranes.
TLDR
Subcellular fractionation of islet cells demonstrated that the calmodulin-activated activity was enriched in a light-particle fraction, but there was no correlation between protein kinase activity and endoplasmic reticulum marker enzyme activity among various subcellular fractions. Expand
Hepatic pyruvate kinase. Regulation by glucagon, cyclic adenosine 3'-5'-monophosphate, and insulin in the perfused rat liver.
TLDR
The changes in the kinetic properties of hepatic pyruvate kinase which follow treating the perfused rat liver with glucagon or cyclic AMP are consistent with the changes observed in the enzyme properties upon phosphorylation in vitro by a clyclicAMP-stimulated protein kinase. Expand
Isozymes of pyruvate kinase in vertebrates: their physical, chemical, kinetic and immunological properties.
  • E. Hall, G. Cottam
  • Biology, Medicine
  • The International journal of biochemistry
  • 1978
TLDR
The physical, chemical, immunologie and kinetic properties of the four isozymes of pyruvate kinase are tabulated, finding the L- and R-isozymes are kinetically similar and immunologically cross-reactive with the M 1 -isozyme. Expand
Calcium–Calmodulin-Dependent Myosin Phosphorylation by Pancreatic Islets
TLDR
Pancreatic islets contain enzyme activity which catalyzes the phosphorylation by MgATP of cardiac, skeletal, or smooth muscle myosin light chains, which may have a key role in coupling stimuli that increase intracellular calcium to the contractile processes involved in insulin secretion. Expand
Association of the src-gene product of rous sarcoma virus with a pyruvate-kinase inactivating factor
TLDR
The hypothesis that substrates of pp 60 src - kinase, essential for cell proliferation, are among the enzymes that control glycolysis is supported. Expand
Studies on the kinetic effects of adenosine-3':5'-monophosphate-dependent phosphorylation of purified pig-liver pyruvate kinase type L.
TLDR
The effect of cyclic-AMP-dependent phosphorylation on the activity of isolated pig liver pyruvate kinase was studied and is thought to be an additional mechanism of inhibition of the enzyme under gluconeogenetic conditions. Expand
Ca2+-dependent protein phosphorylation and insulin release in intact hamster insulinoma cells. Inhibition by trifluoperazine.
TLDR
The data are consistent with a sequence of events involving Ca2+ influx, phosphorylation of P60 by a calmodulin-dependent protein kinase, and resultant insulin secretion. Expand
...
1
2
...