Fluid Mosaic Biomembrane Architecture, Transport Mechanisms & Glycocalyx - Veterinary Biochemistry | Agrigyan

• Erythrocyte Glucose Transporter: GLUT1 is the primary, high-affinity facilitative glucose transporter expressed abundantly on erythrocyte (RBC) membranes ($\sim 5\%$ of total membrane protein) and brain microvessel endothelial cells.
• Major GLUT Transporters:
• GLUT1: RBCs, blood-brain barrier ($K_m \approx 1\text{--}2\text{ mM}$, basal uptake).
• GLUT2: Liver, pancreatic $\beta$-cells, basolateral membrane of renal tubules and enterocytes ($K_m \approx 15\text{--}20\text{ mM}$, high capacity, low affinity).
• GLUT3: Neurons and brain ($K_m \approx 1\text{ mM}$, high affinity).
• GLUT4: Skeletal muscle, cardiac muscle, and adipose tissue (insulin-dependent).
• GLUT5: Small intestine brush border and spermatozoa (specific for fructose).

Correct option: (1) GLUT1