Can GLUT2 transport fructose?
Since GLUT2 can transport fructose and glucose and is upregulated by the presence of glucose, it is a potential candidate for the effect of increased fructose transport in the presence of glu- cose.
Which GLUT is for fructose?
GLUT5
Fructose is transported passively across membranes by a member of the facilitative glucose transporter (GLUT) family, named GLUT5 (19, 20, 72, 98, 137).
Can GLUT1 transport fructose?
The kinetic characteristics of the transport of fructose by human erythrocytes show that they express a high affinity transporter of fructose, and because the transport of fructose is minimally affected by compounds known to block the function of GLUT1 and GLUT2, our results indicate that GLUT5 is the primary …
Is GLUT3 insulin dependent?
Brain Insulin Action As insulin is not required for GLUT1- or GLUT3-mediated glucose transport, insulin is not needed for glucose transport into most brain cells.
How is fructose transported into the cell?
Fructose is transported across the cell membrane of enterocytes via passive transport, in which a membrane protein helps move the fructose without using any ATP molecules. However, both galactose and glucose are transported into the cell by using a sodium-linked secondary active transport system.
What glucose transporter does fructose use?
Fructose Transport GLUT5 is a 501-amino-acid transmembrane protein that transports fructose and glucose molecules. Fructose is transported from the enterocyte into the portal circulation via the basolateral membrane GLUT2 transporter.
Is GLUT5 insulin dependent?
Expression of GLUT5 in the intestine is highly regulated, showing circadian rhythm, dependence on dietary fat and carbohydrate content, and insulin levels.
What is the function of GLUT3?
GLUT3 facilitates the transport of glucose across the plasma membranes of mammalian cells. GLUT3 is most known for its specific expression in neurons and has originally been designated as the neuronal GLUT.
Why is GLUT3 affinity high?
Glycolysis Provides ATP Quickly GLUT3 has a higher affinity for glucose, and a fivefold greater transport capacity to that of GLUT1.
How is fructose absorbed?
Fructose is mostly absorbed in the small intestine through GLUT-5 transporter mediated facilitative diffusion. This is an energy independent process and consequently its absorptive capacity is carrier limited4 Glucose promotes intestinal fructose absorption by solvent drag and passive diffusion2, 5.
Can fructose diffuse across cell membrane?
Glucose, galactose and fructose are tranported out of the enterocyte through another hexose transporter (called GLUT-2) in the basolateral membrane. These monosaccharides then diffuse “down” a concentration gradient into capillary blood within the villus.
Does GLUT2 release insulin?
GLUT2 is the major glucose transporter in pancreatic β-cells and hepatocytes. It plays an important role in insulin secretion fromβ -cells and glucose metabolism in hepatocytes.
What are GLUT1 receptors?
GLUT1 is also a major receptor for uptake of Vitamin C as well as glucose, especially in non vitamin C producing mammals as part of an adaptation to compensate by participating in a Vitamin C recycling process. In mammals that do produce Vitamin C, GLUT4 is often expressed instead of GLUT1.
What is the function of GLUT5 in fructose transport?
GLUT5 allows for fructose to be transported from the intestinal lumen into the enterocyte by facilitated diffusion due to fructose’s high concentration in the intestinal lumen. GLUT5 is also expressed in skeletal muscle, testis, kidney, fat tissue (adipocytes), and brain.
What is GLUT5 in the small intestine?
GLUT5 is a fructose transporter expressed on the apical border of enterocytes in the small intestine. GLUT5 allows for fructose to be transported from the intestinal lumen into the enterocyte by facilitated diffusion due to fructose’s high concentration in the intestinal lumen.
Is fructose intolerance associated with changes in GLUT5 and GLUT2 expression?
Our results suggest that human fructose intolerance may not be associated with marked changes in GLUT5 and GLUT2 expression. However, replication of these results in a larger group of subjects and with measures of transporter activation, as well as membrane and subcellular localization is warranted.
Is GLUT2 involved in apical transport of fructose?
After apical transport mediated by GLUT5, fructose is transported across the basolateral membrane by GLUT2. Recent work by Kellett and Brot-Laroche (82) proposes that GLUT2 is also involved in the apical transport of fructose (see also 5, 15, 136).