Sodium-glucose transport proteins

Sodium-dependent glucose cotransporters are a family of glucose transporter found in the intestinal mucosa of the small intestine (SGLT1) and the proximal tubule of the nephron (SGLT2 and SGLT1). They contribute to renal glucose reabsorption.

Types

SGLT1 and SGLT2 are members of the SLC5A gene family.

Gene	Location	Co-transport ratio and % of glucose reabsorption
SGLT1	Located in the S3 segment of the proximal tubule.	Has a 2Na+:1Glucose co-transport ratio and is responsible for 2% of glucose reabsorption
SGLT2	Is predominately located in the S1 and S2 segments of the proximal tubule.	Has a 1Na+:1Glucose co-transport ratio and is responsible for 98% of glucose reabsorption.

Including SGLT1 and SGLT2, there are total seven members in the human protein family SLC5A, several of which may also be sodium-glucose transporters.

Functions

These proteins use the energy from a downhill sodium gradient to transport glucose across the apical membrane against an uphill glucose gradient. Therefore, these co-transporters are an example of secondary active transport. (The GLUT uniporters then transport the glucose across the basolateral membrane, into the peritubular capillaries.)

See also

• Glucose-galactose malabsorption

References

External links