Sodium-glucose transport proteins
| solute carrier family 5 (sodium/glucose cotransporter), member 1 | |
|---|---|
| Identifiers | |
| Symbol | SLC5A1 |
| Alt. symbols | SGLT1 |
| Entrez | 6523 |
| HUGO | 11036 |
| OMIM | 182380 |
| RefSeq | NM_000343 |
| UniProt | P13866 |
| Other data | |
| Locus | Chr. 22 q13.1 |
| solute carrier family 5 (sodium/glucose cotransporter), member 2 | |
|---|---|
| Identifiers | |
| Symbol | SLC5A2 |
| Alt. symbols | SGLT2 |
| Entrez | 6524 |
| HUGO | 11037 |
| OMIM | 182381 |
| RefSeq | NM_003041 |
| UniProt | P31639 |
| Other data | |
| Locus | Chr. 16 p11.2 |
| solute carrier family 5 (low affinity glucose cotransporter), member 4 | |
|---|---|
| Identifiers | |
| Symbol | SLC5A4 |
| Alt. symbols | SGLT3, SAAT1, DJ90G24.4 |
| Entrez | 6527 |
| HUGO | 11039 |
| RefSeq | NM_014227 |
| UniProt | Q9NY91 |
| Other data | |
| Locus | Chr. 22 q12.1-12.3 |
Sodium-dependent glucose cotransporters (or sodium-glucose linked transporter, SGLT) are a family of glucose transporter found in the intestinal mucosa (enterocytes) of the small intestine (SGLT1) and the proximal tubule of the nephron (SGLT2 in PCT and SGLT1 in PST). They contribute to renal glucose reabsorption. In the kidneys, 100% of the filtered glucose in the glomerulus has to be reabsorbed along the nephron (98% in PCT, via SGLT2). If the plasma glucose concentration is too high (hyperglycemia), glucose is excreted in urine (glucosuria) because SGLT are saturated with the filtered glucose. Glucose is never secreted by a healthy nephron.
The two most well known members of SGLT family are SGLT1 and SGLT2, which are members of the SLC5A gene family. In addition to SGLT1 and SGLT2, there are five other members in the human protein family SLC5A, several of which may also be sodium-glucose transporters.
SGLT2 inhibitors, also called gliflozins, are used in the treatment of type 2 diabetes. Examples include dapagliflozin (Farxiga in US, Forxiga in EU), canagliflozin (Invokana) and empagliflozin (Jardiance).
Firstly, an Na+/K+ ATPase pump on the basolateral membrane of the proximal tubule cell uses ATP molecules to move 3 sodium ions outward into the blood, while bringing in 2 potassium ions. This action creates a downhill sodium ion gradient from the outside to the inside of the proximal tubule cell (that is, in comparison to both the blood and the tubule itself).
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