The Km value in glucose transporters represents:
Facilitative transporters follow Michaelis-Menten-like saturation where velocity depends hyperbolically on concentration. Km operationally defined as substrate concentration where transport rate equals half Vmax maximal rate when all carriers saturated cycling at turnover. It serves as inverse affinity measure: low Km around one millimolar indicates high affinity because half maximal achieved at low concentration suitable for tissues needing glucose despite hypoglycemia typical for GLUT3 in neurons and GLUT1 in erythrocytes. High Km around fifteen to twenty millimolar indicates low affinity wh
Ref: Mueckler & Thorens, Molecular Aspects of Medicine 2013: Glucose Transporters – Km as Half-Vmax Concentration.
