Glucose transporters

Glucose enters cells by facilitated diffusion or by secondary active transport with Sodium(in intestine and kidneys)

Glucose transporters(Glut 1-7) are responsible for facilitated diffusion of glucose across cell membranes.

They differ from sodium dependant glucose transporters(SGLT1 and 2)

Glucose Transporters and their functions

GLUT-1

Basal glucose uptake

Present in brain,kidney,colon,placenta and erythrocytes.

GLUT 2

Beta cell glucose sensor

Transport glucose out of intestinal and renal epithelial cells

Beta cells of pancreas,liver,Small Intestine,Kidneys.

GLUT 3

Basal glucose uptake

Brain,placenta,Kidney

GLUT4

Insulin stimulated glucose uptake

Present in skeletal and cardiac muscle,adipose tissue.

GLUT 5

Fructose transport

Jejunum and sperm

Glut 6

Pseudogene

GLUT 7

Glucose 6 phosphate transporter in endoplasmic reticulum.

Liver

Na+ Glucose co-transporters

SGLT 1

Absorption of glucose from Small Intestine and renal tubules

SGLT 2

Absorption of glucose from renal tubules.

Important points

  1. Basal glucose uptake by- GLUT1 and GLUT3
  2. GLUT 2 is present in beta cells of pancreas, so it controls postprandial hyperglycemia
  3. GLUT4 is insulin dependent so no of GLUT4 decreases after overnight fasting.

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