Write a 100-350 word essay about the enzyme human PGM1. Provide information related to enzyme: i) function, ii) reaction pathways, ii) Location, and iv) diseases. In writing include these four subheadings

### Function
Human PGM1, or phosphoglucomutase 1, is a critical enzyme involved in carbohydrate metabolism. PGM1 catalyzes the reversible conversion of glucose-1-phosphate to glucose-6-phosphate, a key step in glycogenolysis (the breakdown of glycogen) and glycolysis (the breakdown of glucose for energy production). This conversion is essential for maintaining the balance of glucose within the cell, allowing for the efficient storage and release of energy as needed.

### Reaction Pathways
PGM1 operates within both the glycogenolysis and glycolysis pathways. In glycogenolysis, PGM1 converts glucose-1-phosphate, released from glycogen, into glucose-6-phosphate, which can then enter glycolysis or be used for gluconeogenesis. In glycolysis, glucose-6-phosphate is further metabolized to generate ATP, the energy currency of the cell. Additionally, glucose-6-phosphate can enter the pentose phosphate pathway, contributing to the production of NADPH and ribose-5-phosphate, important for anabolic reactions and nucleotide synthesis.

### Location
PGM1 is primarily localized in the cytoplasm, where it performs its role in glucose metabolism. The cytoplasmic location allows PGM1 to efficiently access glucose-1-phosphate and glucose-6-phosphate, facilitating their interconversion as required by the cell’s metabolic demands. This positioning within the cell ensures that PGM1 can rapidly respond to changes in energy needs, supporting processes like muscle contraction, brain function, and overall energy homeostasis.

### Diseases
Mutations in the PGM1 gene lead to a condition known as PGM1 deficiency, or congenital disorder of glycosylation type 1t (CDG-1t). This rare genetic disorder is characterized by symptoms such as muscle weakness, exercise intolerance, hypoglycemia, liver dysfunction, and abnormal glycosylation of proteins. PGM1 deficiency impairs the body's ability to properly convert glucose-1-phosphate to glucose-6-phosphate, disrupting both glycogen metabolism and glycosylation pathways. Understanding PGM1's function is essential for diagnosing and managing PGM1 deficiency, which can sometimes be treated with dietary modifications and supplements like glucose or galactose to mitigate symptoms.