Glucose and Gluconeogenesis Transporters Flashcards
GLUT1
ubiquitous but expressed highly in brain and RBCs
- high affinity
- also located in the cornea, placenta, and cancer cells; these make sense because all have a higher metabolic rate.
- UNREGULATED
GLUT2
Main transporter for liver and pancreas
- lower affinity
- liver is supplied in quantity via Hepatic Portal System, and performs gluconeogenesis for the body; doesn’t need to get high on its own supply
- UNREGULATED
GLUT3
Main transporter in neurons
- high affinity
- the constant APs generated by neurons means they require vast amount of metabolic input to keep concentration gradients across membranes
- UNREGULATED
GLUT4
Present in Skeletal Muscle, adipose tissue, and heart muscle
- for this receptor to become membrane bound then insulin must bind with an insulin receptor causing a cascade of events leading to the binding of vesicles with GLUT4
-REGULATED by insulin
higher affinity than GLUT2 but lower then GLUT3 and GLUT1
T or F: ALL glucose transporters transport against their concentration gradient and thus require energy.
False; passive diffusion with no energy required!
T or F: Exercise favors the placement of GLUT4 on the surface of active cells
True! most studied in skeletal muscle
T1
is a protein that transports glucose 6-phosphate to the liver ER where it can then interact with the Glucose 6-Phosphatase
T2
is a protein that transports inorganic phosphate back into cytosol after Glucose 6-phosphatase uses H2O to convert G6P to glucose
-found in liver
T3
is a protein that transports glucose back to the cytosol from the liver ER
T or F: T1, T2 and T3 work in concert with Glucose 6-phosphatase at the ER membrane
True; Glucose 6-phosphatase is a lumen enzyme but works close to the membrane with the transporters who are transmembrane.
