PMID: 22002721

Authors:

Ismail SA, Chen YX, Rusinova A, Chandra A, Bierbaum M, Gremer L, Triola G, Waldmann H, Bastiaens PI, Wittinghofer A

Title:

Arl2-GTP and Arl3-GTP regulate a GDI-like transport system for farnesylated cargo.

Journal:

Nat Chem Biol. 2011 Oct 16. doi: 10.1038/nchembio.686.

Abstract:

Lipidated Rho and Rab GTP-binding proteins are transported between membranes in complex with solubilizing factors called 'guanine nucleotide dissociation inhibitors' (GDIs). Unloading from GDIs using GDI displacement factors (GDFs) has been proposed but remains mechanistically elusive. PDEdelta is a putative solubilizing factor for several prenylated Ras-subfamily proteins. Here we report the structure of fully modified farnesylated Rheb-GDP in complex with PDEdelta. The structure explains the nucleotide-independent binding of Rheb to PDEdelta and the relaxed specificity of PDEdelta. We demonstrate that the G proteins Arl2 and Arl3 act in a GTP-dependent manner as allosteric release factors for farnesylated cargo. We thus describe a new transport system for farnesylated G proteins involving a GDI-like molecule and an unequivocal GDF. Considering the importance of PDEdelta for proper Ras and Rheb signaling, this study is instrumental in developing a new target for anticancer therapy.