Na+ -GLUCOSE TRANSPORTER-
Sodium-glucose transporters also said to be Na+-glucose cotransporters or symporters (SGLTs).
Sodium-glucose cotransporters (SGLTs) are mediators of glucose uptake across apical cell membranes.
SGLT1mediates almost all sodium-dependent glucose uptake in the small intestine,
In the kidney SGLT2, and to a less extent SGLT1, account for more than 90% and nearly 3%, respectively, of glucose reabsorption from the glomerular ultrafiltrate.
GLUCOSE TRANSPORTER FROM INTESTINAL LUMEN TO EXTRA CELLULAR FLUID IN THE GUT LINING-
The main apical transporter for active glucose uptake in small intestinal epithelial cells is the sodium-dependent glucose co transporter (SGLT).
SGLT1unidirectionally mediates glucose absorption from the intestinal lumen into epithelial cells. SGLT-1 co transports glucose and sodium.
The transporter is initially facing into the lumen and is capable of binding sodium but not glucose. Sodium binds and induces a change that opens the glucose-binding pocket.
The transporter then reorients in the membrane the pockets holding sodium and glucose are moved inside the cell. Sodium dissociates into the cytoplasm due to the conformal change which occurs causing glucose binding to destabilize and dissociate into the cytoplasm. This transcellular pathway is powered by a downhill gradient of Na+ across the apical membrane, maintained by the basolateral Na+/K+ GLUT2 in the basolateral membrane.
The GLUT-2 transports glucose, providing a common exit pathway into the blood.
Fructose is transported across the apical membrane by a specific facilitative transporter, GLUT5. (GLUT5)is a facilitative transporter not an active transport system.
The basolateral transporter GLUT-2 facilitates diffusive transport of intracellular glucose into the interstitium and bloodstream.
Describe the Na+-glucose transporter. Describe how glucose is transported from the intestinal lumen to the extracellular...
Shown in the figure is a sketch of gut epithelial cells. The cells move glucose from the lumen of the gut across thei apical surface and into the cell, and then into the extracellular fluid/blood supply via their basal surface. Using the information in the figure, what type of transporter could be used to move glucose from: 1. The lumen into the cell (and if it requires energy, what is the energy source?). 2. The cell into the extracellular fluid...
The Na glucose symporter transports glucose from the lumen of the small intestine into cells lining the lumen. Transport of 1 glucose molecule is directly coupled to the transport of 2 Nations into the cell. 2 Na*(out) + 1 glucose(out) - 2 Nat(in) + 1 glucose(in) Assume the following conditions at 37 °C: [Nalin - 12 mm, [Na lout = 145 mm, (glucoseJout = 28 pm, and Ay =-72 mV (inside negative). Faraday constant F = 96,485 C/mol, ideal gas...
Based on the figure, describe the mechanisms of uptake of
amino acids from the intestinal lumen into an intestinal cell and
then from the intestinal cell to the bloodstream.
Your answer should include the following terms: primary active
transport, secondary active transport, electrochemical gradient,
concentration gradient, facilitated diffusion, energy.
Question 2. The image below depicts the transport mechanisms used by your intestinal cells to absorb amino acids from your food into your bloodstream. Nat Intestinal lumen Amino acid Nat Amino...
If the sodium concentration of the gut lumen falls below that of the the intestinal epithelium cell. Which of the following would occur. Select one or more: a. the sodium potassium atpase woud be inhbited O b. the cell couldn't get glucose in C. glucose movement from the epithelial cell to the extracelullar fluid would be interupted d. Water wouldn't be absorbed into the cell through osmosis
The glucose transporter that brings glucose into intestinal cells is an example of Simple Diffusion Ion Driven Transport An insulin sensitive transporter Passive Transport An ABC Transporter
You are testing the rate of glucose transport into vesicles using a Na^+-glucose pump. This transporter protein transports Na^+ and glucose in the same direction, and is a coupled transporter such that binding of cither Na^+ or glucose increases the affinity of the transporter to bind the other solute. In experiment 1, you create artificial vesicles that have the Na^+-glucose pump in the membrane. These vesicles have glucose but no Na^+ ions inside. You place these vesicles into a series...
imumseinratio that can be 2. Calculate the maximum (glucose]out achieved by the plasma membrane Na*-glucose symporter of an epithelial cell when [Na']n 12 mM, [Nalout 145 mM, the membrane potential is -50 mV (inside negative), and the temperature is 37 °C Apical surface Basal surface Intestinal Blood lumen 2 K* Microvili Epithelial cell 3 Na+ Na"K+ ATPas Glucose Glucose Glucose uniporter GLUT2 (facilitates Na -glucose symporter (driven by high extracellular Na I downhill efflux)
imumseinratio that can be 2. Calculate...
Glucose is transported into the intestinal cells via cotransport with sodium. Assume the following conditions: Temp = 37oC Sodium (in) = 12.0 mM Sodium (out) = 145 mM Glucose (out) =28 μM ΔΨ = -72mV (inside is negative) a. What is the ΔG for sodium transport? b. What is the upper limit of glucose transport?
Roles of the Na+/ K+ pump 1. Maintain the Nat/K+ concentration gradicnt across the plasma membrane. (That's obvious) 2. It plays a role in maintaining the resting membrane potential. Why? 3. The steep electrochemical gradient of Na+ is used in "coupled active transport" (coupled pumps). If the Nat/K+ pump stops, then these Na+ coupled transport mechanisms will also eventually stop. Explain The apical surface of the epithelial cells that line the lumen of the gut contains a symport that used...
The Na –glucose symport system of
intestinal epithelial cells couples the \"downhill\" transport of
two Na ions into the cell to the \"uphill\" transport of glucose,
pumping glucose into the cell against its concentration gradient.
If the Na concentration outside the cell ([Na ]out) is 155 mM and
that inside the cell ([Na ]in) is 17.0 mM, and the cell potential
is -53.0 mV (inside negative), calculate the maximum ratio of
[glucose]in to [glucose]out that could theoretically be produced if...