4arz

Publication Abstract from PubMed

The heterodimeric Rag GTPases consisting of RagA (or RagB) and RagC (or RagD) are the key regulator activating the target of rapamycin complex 1 (TORC1) in response to the level of amino acids. The heterodimer between GTP-loaded RagA/B and GDP-loaded RagC/D is the most active form that binds Raptor and leads to the activation of TORC1. Here, we present the crystal structure of Gtr1p(GTP)-Gtr2p(GDP), the active yeast Rag GTPase heterodimer. The structure reveals that GTP-to-GDP conversion on Gtr2p results in a large conformational transition of this subunit, including a large scale rearrangement of a long segment whose corresponding region in RagA is involved in binding to Raptor. In addition, the two GTPase domains of the heterodimer are brought to contact with each other, but without causing any conformational change of the Gtr1p subunit. These features explain how the nucleotide-bound statuses of the two GTPases subunits switch the Raptor binding affinity on and off.

Crystal Structure of the Gtr1pGTP-Gtr2pGDP Protein Complex Reveals Large Structural Rearrangements Triggered by GTP-to-GDP Conversion.,Jeong JH, Lee KH, Kim YM, Kim DH, Oh BH, Kim YG J Biol Chem. 2012 Aug 24;287(35):29648-53. Epub 2012 Jul 17. PMID:22807443^[3]

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