SLC5A1

• OMIM: 182380
• UniProt: P13866

Of the sodium / glucose cotransporter 1 ( SGLT1 ) ( gene: SLC5A1 ) is a protein in the cell membrane of mammals, certain monosaccharides and the removed sodium ions by a symport into the cell. He is the man responsible for ensuring that glucose and galactose is absorbed by the body in the intestines. He will also be formed in the kidneys and helps there in the reabsorption of glucose and sodium. Mutations in the SLC5A1 gene can this lead to a transporter deficiency and to rare glucose / galactose malabsorption.

Operation

The transport equation is:

Transportation is generally reversible, as with all carriers, but the low sodium concentration in the cell ensures that inward of symport expires. This is not the case, if the ATP-dependent potassium sodium antiporter fails.

The preferred solutes are glucose and galactose so hexoses with D configuration on the second carbon atom.

The production of the transporter molecule is booted in some cancer cells. There is evidence that SGLT1 plays a role in the defense against bacterial infections in the gut.

Glucose absorption in the small intestine

In the intestinal SGLT -1 is expressed on the uptake of glucose in the mucosal cells in the apical membrane. As glucose is transported to the cells and the gradient between the gut lumen. From the cell to the blood glucose is transported passively via GLUT -2.

Glucose reabsorption in the kidney

SGLT -2, similar to SGLT -1 in structure and function, is expressed only in the kidney. He is closer to the glomerulus, more precisely to see the Pars convoluted proximal tubule. In contrast to the SGLT -1 of the symport requires only one mole of sodium per one mole of solute. Thus, the transport is more favorable to the sodium gradient, also he has a higher transport capacity. Times the glucose gradient between the tubule and blood be built - but only a 100 can. In the pars recta of the proximal tubule, the glucose concentration is already strongly decreased by SGLT -2, hence the gradient is greater for blood. Here the SGLT -1 is expressed, which can build a 10,000 -fold glucose gradient with two moles of sodium in symport. Thus, apart from pathologies such as diabetes, all glucose reabsorbed from the urine.

Regulation

Expression and activity of SGLT1 depends on mechanisms that are sensitive to the extracellular glucose level. Alternatively, the expression of SGLT1 on the sweet taste receptor T1R3 and the G protein gustducin can be booted.