Two regions of GLUT 2 glucose transporter protein are responsible for its distinctive affinity for glucose.

Buchs A, Wu L, Morita H, Whitesell RR, Powers AC
Endocrinology. 1995 136 (10): 4224-30

PMID: 7664639 · DOI:10.1210/endo.136.10.7664639

The glucose transporter in the hepatocyte and pancreatic beta-cell (GLUT 2) has a lower affinity for glucose than other members of the glucose transporter family. To investigate the molecular mechanism for the distinctive affinity of GLUT 2 for glucose, we expressed chimeric GLUT 2 and GLUT 4 proteins in Xenopus oocytes and measured 3-O-methyl-D-glucose transport. In the oocyte system, GLUT 2 had a Km of 31.8 +/- 2.8 mM for 3-O-methyl-D-glucose, whereas GLUT 4 had a Km of 7.2 +/- 2.4 mM under equilibrium exchange conditions. GLUT 4/GLUT 2 chimera that contained the intracellular loop and transmembrane domains 7-12 of GLUT 2 (amino acids 239-497) had a Km similar to that of wild-type GLUT 2. A GLUT 4/GLUT 2 chimera in which the COOH-terminal 30 amino acids of GLUT 4 were replaced with the corresponding region of GLUT 2 had a 2-fold higher Km than GLUT 4, but still had a much lower Km than GLUT 2. These results indicate that both transmembrane domains 7-12 and the COOH-terminus of the protein are responsible for the distinctive glucose affinity of GLUT 2.

MeSH Terms (10)

Animals Female Glucose Glucose Transporter Type 2 Glucose Transporter Type 4 Monosaccharide Transport Proteins Muscle Proteins Oocytes Recombinant Fusion Proteins Xenopus laevis

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