Abstract:
:The glucose transporters (GLUT/SLC2A) are members of the major facilitator superfamily. Here, we generated a three-dimensional model for Glut1 using a two-step strategy: 1), GlpT structure as an initial homology template and 2), evolutionary homology using glucose-6-phosphate translocase as a template. The resulting structure (PDB No. 1SUK) exhibits a water-filled passageway communicating the extracellular and intracellular domains, with a funnel-like exofacial vestibule (infundibulum), followed by a 15 A-long x 8 A-wide channel, and a horn-shaped endofacial vestibule. Most residues which, by mutagenesis, are crucial for transport delimit the channel, and putative sugar recognition motifs (QLS, QLG) border both ends of the channel. On the outside of the structure there are two positively charged cavities (one exofacial, one endofacial) delimited by ATP-binding Walker motifs, and an exofacial large side cavity of yet unknown function. Docking sites were found for the glucose substrate and its inhibitors: glucose, forskolin, and phloretin at the exofacial infundibulum; forskolin, and phloretin at an endofacial site next to the channel opening; and cytochalasin B at a positively charged endofacial pocket 3 A away from the channel. Thus, 1SUK accounts for practically all biochemical and mutagenesis evidence, and provides clues for the transport process.
journal_name
Biophys Jjournal_title
Biophysical journalauthors
Salas-Burgos A,Iserovich P,Zuniga F,Vera JC,Fischbarg Jdoi
10.1529/biophysj.104.047886subject
Has Abstractpub_date
2004-11-01 00:00:00pages
2990-9issue
5eissn
0006-3495issn
1542-0086pii
S0006-3495(04)73771-6journal_volume
87pub_type
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