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