Write a 100-350 word essay about the enzyme human PGM2. Provide information related to enzyme: i) function, ii) reaction pathways, ii) Location, and iv) diseases. In writing include these four subheadings

### Function
Human PGM2, or phosphoglucomutase 2, is an enzyme involved in carbohydrate metabolism, specifically in the interconversion of glucose-1-phosphate and glucose-6-phosphate. Unlike its closely related enzyme PGM1, PGM2 also has the ability to act on other sugar phosphates, such as mannose-1-phosphate and glucose-1,6-bisphosphate. This enzyme plays a critical role in maintaining the balance of glucose and mannose within the cell, which is vital for energy production and glycan synthesis.

### Reaction Pathways
PGM2 functions within both the glycolysis and glycogenolysis pathways. In glycolysis, it facilitates the conversion of glucose-1-phosphate into glucose-6-phosphate, which can then enter the glycolytic pathway to produce ATP, or be used in gluconeogenesis to produce glucose. PGM2 is also involved in the metabolism of mannose, converting mannose-1-phosphate into mannose-6-phosphate, a precursor for glycan biosynthesis. This dual function allows PGM2 to contribute to both energy production and the synthesis of essential cellular structures.

### Location
PGM2 is primarily localized in the cytoplasm, where it accesses substrates like glucose-1-phosphate and mannose-1-phosphate. The cytoplasmic location is essential for its role in energy metabolism, allowing PGM2 to quickly respond to changes in the cell’s energy needs and ensure the proper balance of sugar phosphates. This localization also facilitates its involvement in the glycosylation pathways, which are crucial for protein and lipid modification.

### Diseases
Mutations or deficiencies in PGM2 are less well-characterized compared to PGM1, but disruptions in PGM2 activity could potentially lead to metabolic disorders, particularly those affecting glucose and mannose metabolism. Such disruptions could impair energy production and glycan synthesis, leading to symptoms similar to those seen in other phosphoglucomutase-related disorders, such as muscle weakness, hypoglycemia, and growth delays. Further research is needed to fully understand the impact of PGM2 dysfunction, but its role in critical metabolic pathways suggests that it could be involved in various metabolic and glycosylation disorders.