Glucose Transporters

Question 1

GLUT 1 (Tissue and Function)

Answer 1

Most tissues (especially the brain, RBC), low in muscle

Basal glucose uptake

Facilitative transporter (don’t require ATP)

Question 2

GLUT 2 (Tissue and Function)

Answer 2

Liver, pancreatic β cells, small intestine epithelial cells, kidneys

Monosaccharide (glc/gal/fructose) transporter out of intestinal and renal epithelial cells

Main regulator of blood glucose and its bidirectional

• when high, uptake of glucose into liver/when low, release of glucose into bloodstream
• release glucose into bloodstream from erythrocytes
• in the LIVER, has low affinity but high capacity for glucose transport (so doesn’t compete against the tissues that need glucose more)

Facilitative transporter (don’t require ATP)

Question 3

GLUT 3 (Tissue and Function)

Answer 3

Most tissues (brain, kidney) primary transporter in neurons

Basal glucose uptake (high affinity)

Facilitative transporter (don’t require ATP)

Question 4

GLUT 4 (Tissue and Function)

Answer 4

Skeletal muscle, adipose tissue

INSULIN-stimulated glucose uptake

INSULIN sensitive (remember, NOT in liver)

Facilitative transporter (don’t require ATP)

Question 5

GLUT 5 (Tissue and Function)

Answer 5

Small intestine (jejunum), testis

Fructose transport

doesn’t have high affinity for glucose, instead transports FRUCTOSE

Facilitative transporter (don’t require ATP)