Glucose transporter 2 (GLUT2) also known as solute carrier family 2 (facilitated glucose transporter), member 2 (SLC2A2) is a transmembrane carrier protein that enables protein facilitated glucose movement across cell membranes. It is the principal transporter for transfer of glucose between liver and blood. Unlike GLUT4, it does not rely on insulin for facilitated diffusion. 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. When the glucose concentration in the lumen of the small intestine goes above 30 mM, such as occurs in the fed-state, GLUT2 is up-regulated at the brush border membrane, enhancing the capacity of glucose transport. Basolateral GLUT2 in enterocytes also aids in the transport of fructose into the bloodstream through glucose-dependent cotransport.