Major Facilitator Superfamily Flashcards
What kind of transport does the major facilitator superfamily do?
Passive or secondary active transport
What functions does the major facilitator superfamily complete?
- Nutient Uptake
- Signal transduction
- Drug and noxious compound extraction
Name a member of the major facilitator superfamily
Lactose Permease
Where is lactose permease found?
In the cytoplasmic membrane of bacteria
What is the function of lactose permease?
It transports lactose into the cell when the concentration of glucose is low
What forms the substrate binding pocket of lactose permease?
Network of hydrogen bonds from charged residues
Which amino acid is particularly important in binding sugars?
Tryptophan
Why is tryptophan particularly important in binding sugars in lactose permease?
Because the sugar ring is able to stack on the tryptophan sidechain
How is lactose permease powered?
By translocating H+ from the periplasm to the cytoplasm down a concentration gradient, producing an electrochemical gradient
Where is the lactose transported from and to?
From periplasm to the cytoplasm
Why are His, Asp, and Glu likely to be involved in the proton pathway of lactose permease?
- Can be reversibly protonated
- pKa around physiological pH
What does the lac permease face in the outward conformation?
Periplasm
Where does the lac permease face in the inward conformation?
Cytoplasm
Does H+ or lactose bind first
H+
