Question

4. Glutamine transporters are proteins that, ironically enough, transport glutamine across a membrane. These transporters usually transport sodium along with them. Below is a depiction of the glutamine transport. The binding affinity for glutamine when it's open to the outside is 0.2 mM, while inside it spikes to 5 mM. Na Gln 1 mM 0.4mM Gln 0.7 mM Nat 0.5 mM Which direction would you hypothesize the sodium flow is going in? Why is this sodium transport necessary? When the transport is open to the outside, the binding spot for glutamine contains polar amino acids. Upon opening to the inside, the glutamine gets shifted and moved into a hydrophobic pocket. How does that help facilitate the transportation across the membrane? a. b.

Answer 1

Answer a- The glutamine is a acidic amino acid and have negative charge on it. When glutamine move inside the cell then it creates a extra negative charge inside the membrane of cell which may lead disturbance of electrical polarity. So to avoid theses disturbance in membrane charge polarity a sodium ion move inside the cell for to balance the charge.

Answer b- The plasma membrane is consist of lipid which are non polar. So movement of polar molecule across membrane occurs by transporter. 1^st glutamine bind with polar amino acids of the receptor on outside the cells and then after binding it get shifted in hydrophobic core of receptor. After that a conformational change in receptor occurs and its lead to release of glutamine inside the cells.