SGLT1SLC5A1

SGLT1SLC5A1 refers to the sodium-glucose cotransporter 1 (SGLT1), a protein encoded by the SLC5A1 gene. SGLT1 is a member of the solute carrier family 5 and functions as a sodium-dependent transporter for glucose and galactose. It is primarily expressed on the apical membrane of enterocytes in the small intestine and to a lesser extent in the kidney’s proximal tubules, where it helps reabsorb filtered glucose.

The transport mechanism of SGLT1 relies on the sodium gradient across the cell membrane. It couples the inward movement of Na+ with the uptake of glucose or galactose against their concentration gradient, using energy stored in the Na+ electrochemical gradient established by the Na+/K+-ATPase. SGLT1 has high affinity but relatively low transport capacity compared with other glucose transporters, enabling efficient absorption of dietary sugars at lower lumenal concentrations.

In the intestine, SGLT1 is the principal transporter for the luminal absorption of glucose and galactose from digested carbohydrates, contributing to postprandial glucose availability. In the kidney, SGLT1 participates in reabsorbing a portion of the filtered glucose in the proximal tubule, serving as a complementary pathway alongside SGLT2.

Genetically inherited mutations in SLC5A1 cause glucose-galactose malabsorption (GGM), an autosomal recessive disorder characterized by severe osmotic diarrhea, dehydration, and malnutrition after ingestion of glucose or galactose. Management requires a diet free of glucose and galactose. Beyond its physiological role, SGLT1 is a target of pharmaceutical research; inhibitors of SGLT1, including dual SGLT1/2 inhibitors, are being explored for managing postprandial hyperglycemia and metabolic effects, though they can cause gastrointestinal side effects such as diarrhea.