GLUT2 has high capacity for glucose but low affinity (high KM, ca. 15–20 mM) and thus functions as part of the “glucose sensor” in the pancreatic β-cells of rodents, though in human β-cells the role of GLUT2 seems to be a minor one. It is a very efficient carrier for glucose. GLUT2 also carries glucosamine.
Does GLUT2 have a high affinity for glucose?
The K(m)s for glucosamine and glucose of GLUT1 and GLUT4 were similar. In contrast, GLUT2 had a much higher apparent affinity for glucosamine than for glucose (K(m)=0.8+/-0.1 mM vs. approximately 17-20 mM).
Which glut has the lowest affinity for glucose?
GLUT2 have a lower affinity for glucose and is essential for the liver and the pancreas to regulate the blood glucose level. With a lower affinity transporter, glucose will not be taken up immediately by the liver/pancreas while reserving for the high glucose demanding organs (e.g brain, neurons, red blood cells).
Which glut has the higher affinity for glucose?
GLUT3 has a higher affinity for glucose and greater transport capacity than GLUT1, making it important in tissues with a high rate of metabolic activity.
Is GLUT2 glucose dependent?
In the nervous system, GLUT2-dependent glucose sensing controls feeding, thermoregulation and pancreatic islet cell mass and function, as well as sympathetic and parasympathetic activities.
What is the role of GLUT2?
GLUT2 is the major glucose transporter inβ -cells of pancreatic islets and hepatocytes. In both cell types, GLUT2 mediates the facilitated diffusion of glucose across the cell membranes, and then intracellular glucose metabolism is initiated by the glucose-phosphorylating enzyme, hexokinase IV or glucokinase.
What is the difference between GLUT2 and GLUT 4?
Does GLUT 2 transport glucose OUT of the cell, whereas glut4 transports glucose INTO the cell? And GLUT5 transports fructose into the cell?
What is the difference between GLUT 1 and GLUT 2?
GLUT-1 was more effectively induced when glucose was low, and GLUT-2 expression was more pronounced when glucose was high in the culture media. Another difference between the two glucose transporters was that GLUT-2 expression was increased while GLUT-1 expression was decreased as culturing continued as long as 7 days.
Where are GLUT 2 receptors found?
GLUT2 is a facilitative glucose transporter located in the plasma membrane of the liver, pancreatic, intestinal, kidney cells as well as in the portal and the hypothalamus areas.
Where is GLUT3 found?
GLUT3 is predominantly located in the apical trophectoderm plasma membrane (arrow), whereas GLUT1 is localized to the basolateral surfaces of both the trophectoderm and inner cell mass cells (arrowheads).
Why does GLUT2 have low affinity?
Levels of this isoform are quite low in the fetus. GLUT2 has 55% amino acid identity with sequences of GLUT1, and it has a similar structure and orientation in the plasma membrane. … The most characteristic feature of this isoform is its uniquely high Km for glucose (~17 mM), resulting in very low affinity for glucose.
Does GLUT2 use ATP?
Function/physiology of SGLTs and GLUTs
SGLTs do not directly utilize ATP to transport glucose against its concentration gradient; rather, they must rely on the sodium concentration gradient generated by the sodium–potassium ATPase as a source of chemical potential.
Does GLUT3 require insulin?
As insulin is not required for GLUT1- or GLUT3-mediated glucose transport, insulin is not needed for glucose transport into most brain cells. Insulin does, however, play a role as a neuroregulatory peptide, and this role is slowly being unraveled.
How GLUT2 enable facilitated diffusion of glucose?
Once inside the epithelial cells, glucose reenters the bloodstream through facilitated diffusion through GLUT2 transporters. Hence reabsorption of glucose is dependent upon the existing sodium gradient which is generated through the active functioning of the NaKATPase.
Does insulin effect GLUT2?
RESULTS AND CONCLUSIONS—In Caco-2/TC7 cells, insulin action diminished the transepithelial transfer of sugar and reduced BBM and basolateral membrane (BLM) GLUT2 levels, demonstrating that insulin can target sugar absorption by controlling the membrane localization of GLUT2 in enterocytes.
Why is GLUT2 appropriate for hepatocytes?
GLUT2 is the major glucose transporter of hepatocytes in rodents and humans [19, 49]. The generally accepted role of this transporter is to take up glucose during the absorptive phase and to release it in the blood during fasting.