Function
Firstly, the Na+/K+ ATPase pump on the basolateral membrane of the proximal tubule cell uses ATP to move 3 sodium outward into the blood, while bringing in 2 potassium. This creates a downhill sodium gradient inside the proximal tubule cell in comparison to both the blood and the tubule. The SGLT proteins use the energy from this downhill sodium gradient created by the ATPase pump 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.) Both SGLT1 and SGLT2 are known as symporters, since both sodium and glucose are transported in the same direction across the membrane.
Read more about this topic: Sodium-glucose Transport Proteins
Famous quotes containing the word function:
“We are thus able to distinguish thinking as the function which is to a large extent linguistic.”
—Benjamin Lee Whorf (1897–1934)
“The mother’s and father’s attitudes toward the child correspond to the child’s own needs.... Mother has the function of making him secure in life, father has the function of teaching him, guiding him to cope with those problems with which the particular society the child has been born into confronts him.”
—Erich Fromm (1900–1980)
“The uses of travel are occasional, and short; but the best fruit it finds, when it finds it, is conversation; and this is a main function of life.”
—Ralph Waldo Emerson (1803–1882)