In order to produce glucose out of glycogen when extra glucose is needed quickly
ID: 259069 • Letter: I
Question
In order to produce glucose out of glycogen when extra glucose is needed quickly, glycogen is degraded to release glucose-1-phosphate (which is converted back to glucose-6- phosphate and then glucose). This conversion of glycogen to G-1-P happens mostly in cytosol, which is extensively covered in the lecture, but there is a different subcellular location where the same process happens and the genetic defects in this process lead to a disease called Pompe Disease (which causes accumulation of glycogen and is the first of >40 glycogen storage diseases identified by Dutch pathologist Joannes Cassianus Pompe).
(1) Name the subcellular location and the enzyme responsible for this conversion in this location. (2 points)
(2) This enzyme cleaves ?-1,4 and ?-1,6 glycosidic linkages of glycogen. Explain the importance of the cleavage of both linkages in lysosome as compared with cytosol. (5 points)
2. In order to produce glucose out of glycogen when extra glucose is needed quickly, glycogen is degraded to release glucose-1-phosphate (which is converted back to glucose-6- phosphate and then glucose). This conversion of glycogen to G-1-P happens mostly in cytosol, which is extensively covered in the lecture, but there is a different subcellular location where the same process happens and the genetic defects in this process lead to a disease called Pompe Disease (which causes accumulation of glycogen and is the first of >40 glycogen storage diseases identified by Dutch pathologist Joannes Cassianus Pompe) (1) Name the subcellular location and the enzyme responsible for this conversion in this location. (2 points) (2) This enzyme cleaves a-1.4 and a-1,6 glycosidic linkages of glycogen. Explain the importance of the cleavage of both linkages in lysosome as compared with cytosol. (5 points)Explanation / Answer
Answer 1. Lysosome is subcellular and acid maltase or acid alpha glucosidase enzyme is responsible for conversion of glycogen to glucose in lysosome.
Answer 2. Acid maltase cleaved alpha 1-4 and alpha 1-6 glycosidic linkage of glycogen. This enzymes cleaved around 1-3% of cellular glycogen. So defect in this gene result in accumulation of glycogen and result in cell death. So the cleavage is also essentially cleaved by lysosome.