Sodium/glucose cotransporter 1

Sodium/glucose cotransporter 1 (also known as SGLT1) is a protein that in humans is encoded by the SLC5A1 gene. SGLT1 is a member of the sodium:glucose cotransporter family which are sodium-dependent glucose transport proteins. SGLT1 is responsible for the uptake of glucose and galactose in the small intestine, and thus plays a significant role in overall glucose homeostasis.

Structure

SGLT1 is a transmembrane protein that exists in the cell membrane of enterocytes in the small intestine. It is composed of 664 amino acids and has 14 transmembrane domains with both the N and C terminus located intracellularly. The protein also has a large extracellular loop between the 9th and 10th transmembrane domains.

Function

SGLT1 functions as a symporter, meaning it transports two different types of ions or molecules in the same direction across the membrane. In this case, it transports two sodium ions and one glucose or galactose molecule into the cell. This is an active transport mechanism, as it requires energy in the form of a sodium gradient across the membrane. This gradient is maintained by the sodium-potassium pump, which pumps sodium out of the cell and potassium into the cell.

Clinical significance

Mutations in the SLC5A1 gene can lead to glucose-galactose malabsorption, a rare genetic disorder characterized by severe diarrhea and dehydration due to the inability to absorb glucose and galactose in the small intestine. Treatment involves a diet free of glucose and galactose.

SGLT1 inhibitors are currently being researched as potential treatments for diabetes, as they could reduce the reabsorption of glucose in the kidneys and thus lower blood glucose levels.

See also

• Sodium-glucose transport proteins
• Glucose-galactose malabsorption
• Sodium-potassium pump