title: Structural Basis of Dimeric Rasip1 RA Domain Recognition of the Ras Subfamily of GTP-Binding Proteins.
abstract: Ras-interacting protein 1 (Rasip1) is an endothelial-specific Rap1 and Ras effector, important for vascular development and angiogenesis. Here, we report the crystal structure of the Rasip1 RA domain (RRA) alone, revealing the basis of dimerization, and in complex with Rap1 at 2.8 Å resolution. In contrast to most RA domains, RRA formed a dimer that can bind two Rap1 (KD= 0.9 μM) or Ras (KD= 2.2 μM) molecules. We solved the Rap1-RRA complex and found that Rasip1 binds Rap1 in the Switch I region, and Rap1 binding induces few conformation changes to Rasip1 stabilizing a β strand and an unstructured loop. Our data explain how Rasip1 can act as a Rap1 and Ras effector and show that Rasip1 defines a subgroup of dimeric RA domains that could mediate cooperative binding to membrane-associated Ras superfamily members.
authors.affiliation: Department of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA. Electronic address: agingras@ucsd.edu.
authors.forename: Alexandre R
authors.initials: AR
authors.lastname: Gingras
authors.affiliation: Department of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA.
authors.forename: Wilma
authors.initials: W
authors.lastname: Puzon-McLaughlin
authors.affiliation: Sanford Burnham Prebys Medical Discovery Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA.
authors.forename: Andrey A
authors.initials: AA
authors.lastname: Bobkov
authors.affiliation: Department of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA.
authors.forename: Mark H
authors.initials: MH
authors.lastname: Ginsberg
mesh_terms: D001665:Binding Sites; D019281:Dimerization; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000737:chemistry* / Q000378:metabolism*; D008958:Models, Molecular; D011485:Protein Binding; D000072417:Protein Domains; D017433:Protein Structure, Secondary; D020827:rap1 GTP-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D018631:ras Proteins / Q000737:chemistry / Q000378:metabolism*
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; C487329:RASIP1 protein, human; D020827:rap1 GTP-Binding Proteins; D018631:ras Proteins
keywords: GTP-binding proteins; Radil; Rap; Ras; Ras-association (RA) domain; Ras-interacting protein 1 (Rasip1); crystal structure; dimer; heart of glass (HEG1); rain