Galactose-1-phosphate uridylyltransferase

DGalactose Fischer

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D-glucose chain (Fischer)

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GALT

Galactose-1-phosphate uridylyltransferase (GALT) is an enzyme that plays a crucial role in the metabolism of galactose, a type of sugar found in milk and other dairy products, as well as in various fruits and vegetables. This enzyme facilitates the conversion of galactose-1-phosphate and uridine diphosphate glucose (UDP-glucose) into uridine diphosphate galactose (UDP-galactose) and glucose-1-phosphate. This reaction is a part of the Leloir pathway, the main pathway for galactose metabolism.

Function

The primary function of GALT is to ensure the efficient use of galactose obtained from the diet. By converting galactose-1-phosphate into UDP-galactose, GALT plays a vital role in energy production and the synthesis of glycogen, glycoproteins, and glycolipids. These molecules are essential for various cellular functions, including cell signaling, structural integrity, and energy storage.

Genetic and Health Implications

Mutations in the GALT gene, which encodes the GALT enzyme, can lead to a condition known as Galactosemia. This genetic disorder prevents the proper metabolism of galactose, leading to the accumulation of toxic substances in the blood, liver, and brain. Early symptoms of galactosemia include feeding difficulties, failure to thrive, jaundice, and liver enlargement. If left untreated, the condition can result in cataracts, intellectual disability, and even life-threatening infections.

Diagnosis and Treatment

The diagnosis of galactosemia typically involves screening newborns for elevated levels of galactose-1-phosphate in the blood. Confirmatory tests include measuring the activity of the GALT enzyme in red blood cells. Treatment for galactosemia involves a lifelong diet that restricts galactose intake, which helps prevent the symptoms and complications associated with the disorder.

Biochemical Significance

The study of GALT and its role in galactose metabolism has broader implications for understanding carbohydrate metabolism and genetic metabolic disorders. Research in this area can lead to improved diagnostic methods and treatments for galactosemia and similar conditions.