III.3.A. Transporters playing a role in Glu uptake and release

GLUT participate in Glu uptake.

Fourteen GLUT proteins have been described in the human. The most important of them:

GLUT-1

Present in:                   nervous system and red blood cells

Transport kinetics:      constant

Glu affinity:                high

Direction of uptake:    one direction

GLUT-2

Present in:                  brain, intestinal epithelium, pancreatic B cells and kidneys

Transport kinetics:      high

Glu affinity:                low

Direction of uptake:    one direction

GLUT-3

Present in:                   liver, brain and testis

Transport kinetics:      variable

Glu affinity:                 high

Direction of uptake:    in both directions

GLUT-4

Present in:                   muscle, fat and heart

Transport kinetics:      variable 20-30 x (higher than that of GLUT-1)

Glu affinity:                 high

Direction of uptake:    one direction