GLUTs are passive membrane transporters that pass glucose and other similar substrates like fructose, mannose, ascorbate, and urate ions. They have been classified into three classes based on their sequence similarity and substrate affinity. The Class I GLUTs (1–4 and 14) facilitate the uptake of glucose and other hexoses, but not fructose. The Class II GLUTs (5, 7, 9 and 11) are fructose transporters, and Class III GLUTs (6, 8, 10, 12, and 13 (HMIT1)) are structurally atypical members.

Unit 3,

Reference: Ismail A, Tanasova M. Importance of GLUT Transporters in Disease Diagnosis and Treatment. Int J Mol Sci. 2022;23(15):8698. Published 2022 Aug 4.