GLUT 2 is a transmembrane carrier protein and gene which is involved in passive transport of glucose over cellular membranes of the liver, pancreatic beta cells, hypothalamus, basolateral membrane small intestine. It has high capacity but low affinity (high Km, ca. 5 mM) part of "the glucose sensor" in ß-cells. It is a very efficient carrier for glucose, and may also carry the vital enzyme glucosamine (because mouse embryos lacking this glucose carrier protein/gene- and it's suspected capacity to transport glucosamine- soon die). According to genetics researchers in neonatal and maternal-fetal medicine at Harvard University Medical School and Beth-Israel Deaconess Hospital Medical Center, this creates a problem for diabetic pregnancies in which glucose levels in the woman are uncontrolled, exposing her fetus to the possibility of neural tube and cardiac defects in the early-developing brain, spine, and heart. Fructose uses the GLUT5 transporter. This receptor is insulin-independent.
