Transport of glucose across the epithelium, lumen and as it
exits the epithelial cell.
Epithelial
- line the gut
Binding
- the binding of one enhances the binding of the other.
Symport
- pump moves both solutes in the same direction across the
membrane.
Antiport
- moves them in opposite directions.
Uniport
- A transporter that ferries only one type of solute across the
membrane down its concentration gradient. The glucose transporter
(below) is an example of a uniport.
A gradient of any solute across a
membrane, like the electrochemical Na+ gradient
generated by the Na+ pump, can be used to drive the
active transport of a second molecule. The downhill
movement of the first solute down its gradient provides
the energy to power the uphill transport of the second
solute.
The active transporters that work in this way
are called gradient-driven pumps. They can couple the
movement of one inorganic ion to that of another. The
Electrochemical Na+ Gradient Drives the Transport of
Glucose Across the Plasma Membrane of Animal
Cells.
Gut epithelial cells have two types of glucose transporters located
at opposite ends of the cell.
Apical domain of the plasma membrane
- glucose–Na+ symports.
Basal and lateral domains of the plasma membrane
- passive glucose uniports.
Two types of glucose transporters enable gut epithelial cells to
transfer glucose across the epithelial lining of the gut.
- Na+
- Na+ electrochemical gradient steep
A glucose Na+ symport uses the electrochemical Na+ gradient to
drive the active import of glucose.
+ quick recap