Glycogen phosphorylase isoenzyme BB

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Glycogen phosphorylase isoenzyme BB (abbreviation: GPBB) is an isoenzyme of glycogen phosphorylase. This isoform of the enzyme exists in cardiac (heart) and brain tissue.

The enzyme is one of the "new cardiac markers" which are discussed to improve early diagnosis in acute coronary syndrome. A rapid rise in blood levels can be seen in myocardial infarction and unstable angina.

Other enzymes related to glycogen phosphorylase are abbreviated as GPLL (liver) and GPMM (muscle).

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Glycogen phosphorylase, brain, is an enzyme that in humans is encoded by the PYGB gene on chromosome 20. The protein encoded by this gene is a glycogen phosphorylase found predominantly in the brain. The encoded protein forms homodimers which can associate into homotetramers, the enzymatically active form of glycogen phosphorylase. The activity of this enzyme is positively regulated by AMP and negatively regulated by ATP, ADP, and glucose-6-phosphate. This enzyme catalyzes the rate-determining step in glycogen degradation. [provided by RefSeq, Jul 2008]

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