What is PYGL gene?
The PYGL gene provides instructions for making an enzyme called liver glycogen phosphorylase. This enzyme breaks down a complex sugar called glycogen. Liver glycogen phosphorylase is one of three related enzymes that break down glycogen in cells; the other glycogen phosphorylases are found in the brain and in muscles.
What does glycogen phosphorylase do?
The enzyme glycogen phosphorylase is fundamentally important in glucose metabolism. It catalyzes the release of glucose monomers from the glycogen polymer stored in the liver (glycogenolysis). Glycogen is broken down by GP to produce glucose-1-phosphate (G-1-P) in a reaction that does not require ATP.
What type of enzyme is phosphorylase?
Phosphorylases are a special group of non-Leloir-type glycosyltransferases that catalyze the phosphorylysis of the glycosidic bond at the nonreducing end, releasing a sugar 1-phosphate residue.
Which enzyme is deficient in McArdle disease?
McArdle disease is an inherited disease. It results from changes (mutations) in the gene for the enzyme muscle phosphorylase. Your muscle cells can’t make this enzyme. So they can’t break down glycogen into glucose.
What chromosome is muscle glycogen phosphorylase gene found on?
Glycogen phosphorylase, liver form (PYGL), also known as human liver glycogen phosphorylase (HLGP), is an enzyme that in humans is encoded by the PYGL gene on chromosome 14.
How does glycogen phosphorylase?
In muscle, glycogen phosphorylase is activated by hormones and neural signals such as epinephrine, that stimulate phosphorylase kinase which phosphorylates the Ser-14 residue of the protein. The activated kinase in turn activates the glycogen phosphorylase enzyme by phosphorylating the Ser-14 residue.
What is the function of glycogen phosphorylase and how is its activity different from that of amylase?
The mechanism of inhibition of a-amylase activity depends on competition for the altered substrate: glycogen phosphorylase degrades the glycogen-protein complex as well as free glycogen, whereas a-amylase acts mainly on the free polysaccharide.
Is phosphorylase a hydrolase?
Thus, the two substrates of this enzyme are phosphorylase a and H2O, whereas its two products are phosphorylase b and phosphate. This enzyme belongs to the family of hydrolases, specifically those acting on phosphoric monoester bonds. The systematic name of this enzyme class is [phosphorylase a] phosphohydrolase.
Is phosphatase a hydrolase or transferase?
In biochemistry, a phosphatase is an enzyme that uses water to cleave a phosphoric acid monoester into a phosphate ion and an alcohol. Because a phosphatase enzyme catalyzes the hydrolysis of its substrate, it is a subcategory of hydrolases.
What causes glycogen storage disease?
Glycogen storage diseases are caused by a genetic enzyme defect that is inherited from both parents. Normally, enzymes help convert glucose into glycogen for storage. Other enzymes convert the glycogen back to glucose when quick energy is needed, as in exercise.
What causes glycogen storage disease type 6?
GSD6 is caused by harmful changes (mutations) in the PYGL gene. This gene is responsible for telling the body how to make an enzyme called liver glycogen phosphorylase. This enzyme is responsible for breaking down glycogen. Glycogen is a form of energy that comes from carbohydrates and is stored in the liver.