Identification of the Human Erythrocyte Glucose Transporter (GLUT1) ATP Binding Domain: A Dissertation

The human erythrocyte glucose transport protein (GLUT1) interacts with, and is regulated by, cytosolic ATP. This study asks the following questions concerning ATP modulation of GLUT1 mediated sugar transport. 1) Which region(s) of GLUT1 form the adenine nucleotide-binding domain? 2) What factors influence ATP modulation of sugar transport? 3) Is ATP interaction with GLUT1 sufficient for sugar transport regulation? The first question was addressed through peptide mapping, n-terminal sequencing, and alanine scanning mutagenesis of GLUT1 using [32P]-azidoATP, a photoactivatable ATP analog. We then used a combination of transport measurements and photolabeling strategies to examine how glycolytic intermediates, pH, and transporter oligomeric structure affect ATP regulation of sugar transport. Finally, GLUT1 was reconstituted into proteoliposomes to determine whether ATP is sufficient for the modulation of GLUT1 function in-vitro. This thesis presents data supporting the hypothesis that residues 332-335 contribute to the efficiency of adenine nucleotide binding to GLUT1. In addition, we show that AMP, acidification, and conversion of the transporter to its dimeric form antagonize ATP regulation of sugar transport. Finally, we present results that support the proposal that ATP interaction with GLUT1 is sufficient for transport modulation