3gi8

Publication Abstract from PubMed

Amino acid, polyamine, and organocation (APC) transporters are secondary transporters that play essential roles in nutrient uptake, neurotransmitter recycling, ionic homeostasis, and regulation of cell volume. Here, we present the crystal structure of apo-ApcT, a proton-coupled broad-specificity amino acid transporter, at 2.35 A resolution. The structure contains 12 transmembrane helices, with the first 10 consisting of an inverted structural repeat of 5 transmembrane helices like LeuT. The ApcT structure reveals an inward-facing, apo state and an amine moiety of Lys158 located in a position equivalent to the Na2 ion of LeuT. We propose that Lys158 is central to proton-coupled transport and that the amine group serves the same functional role as the Na2 ion in LeuT, thus demonstrating common principles among proton- and sodium-coupled transporters.

Structure and Mechanism of a Na+ Independent Amino Acid Transporter.,Shaffer PL, Goehring A, Shankaranarayanan A, Gouaux E Science. 2009 Jul 22. PMID:19608859^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.