Fructose absorption into enterocytes uses which apical transporter?

• A. GLUT5
• B. SGLT1
• C. GLUT1
• D. GLUT2

Answer: (A)

Fructose is taken up from the intestinal lumen into the enterocyte by GLUT5 on the apical membrane. GLUT5 is a facilitated-diffusion transporter that specifically handles fructose, moving it along its concentration gradient into the cell. This differs from glucose and galactose, which enter via SGLT1 on the apical surface using a sodium co-transport mechanism. GLUT1 is a general glucose transporter found in many tissues, not the main apical route for intestinal fructose. GLUT2 serves mainly the basolateral exit of monosaccharides into the bloodstream (though it can appear on the apical membrane in some high-carbohydrate situations, the classic apical entry for fructose is GLUT5).