GLUTs (Glucose transporters ) are proteins comprising 12 membrane-spanning regions. GLUTs transport glucose across the plasma membrane by means of a facilitated diffusion mechanism.
GLUT1 (SLC2A1), a uniporter protein, facilitates the transport of glucose across the plasma membranes of mammalian cells. GLUT2 (SLC2A2) is a transmembrane carrier protein that enables protein facilitated glucose movement across cell membranes. GLUT3 (SLC2A3), mainly present in the brain, has high affinity for glucose. GLUT3 facilitates the transport of glucose across the plasma membranes of mammalian cells. GLUT4 (SLC2A4) is found in the heart, skeletal muscle, adipose tissue, and brain. GLUT4 is an insulin-responsive glucose transporter.