BRAIN GLYCOGEN PHOSPHORYLASE IN HYPOXIC-ISCHEMIC EVENTS

Project: Research project

Description

Brain glycogenolysis plays a critical role in meeting the acute energy
requirements of the central nervous system during hypoxic-ischemic events,
hypoglycemia, and seizures. Recent evidence suggests that brain glycogen
phosphorylase has important regulatory differences from the isoenzymes
expressed by skeletal muscle and liver. These regulatory differences, in
particular inhibition of brain phosphorylase by glucose, has important
implications into understanding control of brain glycogenolysis during
acute alterations in cellular metabolism of brain tissue. We propose to identify and determine the amino sequence of brain glycogen
phosphorylase in rabbit using recombinant DNA techniques. Our laboratory
has determined the x-ray crystallographic structure of rabbit muscle
phosphorylase a to 2.1 Angstrom resolution. We have co-crystallized
regulatory ligands with the enzyme, identified five regulatory sites for
this enzyme, and have elucidated many of the molecular mechanisms governing
their allosteric control. We will compare the amino acid sequence of
rabbit brain phosphorylase with the known sequence and tertiary structure
of the rabbit muscle isoenzyme. This should allow us by comparison to
account for the maintenance or alteration of regulatory sites for the brain
isoenzyme. We will partially purify brain phosphorylase in rabbit from the
other phosphorylase isoenzymes and examine the regulatory properties of
purine compounds, AMP, ATP, as well as selective gluconeogenic substrates.
DNA probes encoding for fragments of brain and skeletal muscle glycogen
phosphorylase will be used for in situ hybridization to regions of the
neocortex to localize these isoenzymes to neuronal and glial elements
within the central nervous system.
StatusFinished
Effective start/end date9/1/858/31/87

Funding

  • National Institutes of Health
  • National Institutes of Health

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Glycogen Phosphorylase
Phosphorylases
Brain
Isoenzymes
Rabbits
Glycogenolysis
Skeletal Muscle
Central Nervous System
Recombinant DNA
DNA Probes
Enzymes
Adenosine Monophosphate
Hypoglycemia
Neuroglia
In Situ Hybridization
Amino Acid Sequence
Seizures
Adenosine Triphosphate
Maintenance
X-Rays

ASJC

  • Medicine(all)
  • Neuroscience(all)