GLUT4

Glucose transporter type 4 (GLUT4), also known as solute carrier family 2, facilitated glucose transporter member 4, is a <a href="/facts/Protein/Jxmagu3E">protein</a> encoded, in humans, by the SLC2A4 <a href="/facts/Gene/e1swwPY6">gene</a>. GLUT4 is the <a href="/facts/Insulin/oXG0myt1">insulin</a>-regulated <a href="/facts/Glucose_transporter/3B7IGR9Q">glucose transporter</a> found primarily in <a href="/facts/Adipose/PxxedB6e">adipose</a> tissues and <a href="/facts/Striated_muscle/WYfQuhID">striated muscle</a> (skeletal and cardiac). GLUT4 is distinctive because it is predominantly stored within intracellular vesicles, highlighting the importance of its trafficking and regulation as a central area of research. The first evidence for this glucose transport protein was provided by <a href="/facts/David_James_(cell_biologist)/pDYgkckF">David James</a> in 1988. The gene that encodes GLUT4 was cloned and mapped in 1989.
At the cell surface, GLUT4 permits the facilitated diffusion of circulating glucose down its concentration gradient into muscle and fat cells. Once within cells, glucose is rapidly <a href="/facts/Phosphorylated/LXUEEeIL">phosphorylated</a> by <a href="/facts/Glucokinase/vYtNlPek">glucokinase</a> in the liver and <a href="/facts/Hexokinase/upUIvz6J">hexokinase</a> in other tissues to form <a href="/facts/Glucose-6-phosphate/2KybIvaN">glucose-6-phosphate</a>, which then enters <a href="/facts/Glycolysis/a5ApxLoG">glycolysis</a> or is polymerized into glycogen. Glucose-6-phosphate cannot diffuse back out of cells, which also serves to maintain the concentration gradient for glucose to passively enter cells.

GLUT4 open-in-new

GLUT4