The Erythrocyte/Brain Glucose Transporter (GLUT1) May Adopt a Two–Channel Transmembrane α/β Structure.

Abstract

There are two models of topology for the membrane domains of the erythrocyte/brain facilitative glucose transporter, GLUT1. The first is composed of 12 membrane–spanning α–helices, the second of 16 membrane-spanning β-strands. We have used Jähnig′s and Eisenberg′s methods to identify possible transmembrane segments (10 spanning α-helices and 4 β-strands). The topology proposed is more consistent with available experimental data from FTIR, CD and map** experiment than the previous models . We suggest that GLUT1 might form two channels, one of which is responsible for glucose transport. This agrees with the theoretical and experimental arguments. Finally, an analysis of the mutation periodicity and of the mean hydrophobicity for the GLUT family is provided in order to evaluate the packing of the protein in the membrane.