1UAD

Crystal structure of the RalA-GppNHp-Sec5 Ral-binding domain complex

Summary for 1UAD

• Entry DOI: 10.2210/pdb1uad/pdb
• Related: 1C1Y 1HE8 1K8R 1LFD
• Descriptor: Ras-related protein Ral-A, Exocyst complex component Sec5, MAGNESIUM ION, ... (5 entities in total)
• Functional Keywords: small gtp-binding protein, immunogloblin-like fold, beta-sandwich, endocytosis-exocytosis complex, endocytosis/exocytosis
• Biological source: Homo sapiens (human); More
• Cellular location: Cell surface: P11233
• Total number of polymer chains: 4
• Total formula weight: 62154.13

Authors

Fukai, S.,Matern, H.T.,Scheller, R.H.,Brunger, A.T. (deposition date: 2003-03-09, release date: 2003-07-15, Last modification date: 2023-10-25)

Primary citation

Fukai, S.,Matern, H.T.,Jagath, J.R.,Scheller, R.H.,Brunger, A.T.
Structural basis of the interaction between RalA and Sec5, a subunit of the Sec6/8 complex
EMBO J., 22:3267-3278, 2003

PubMed Abstract: The sec6/8 complex or exocyst is an octameric protein complex that functions during cell polarization by regulating the site of exocytic vesicle docking to the plasma membrane, in concert with small GTP-binding proteins. The Sec5 subunit of the mammalian sec6/8 complex binds Ral in a GTP-dependent manner. Here we report the crystal structure of the complex between the Ral-binding domain of Sec5 and RalA bound to a non-hydrolyzable GTP analog (GppNHp) at 2.1 A resolution, providing the first structural insights into the mechanism and specificity of sec6/8 regulation. The Sec5 Ral-binding domain folds into an immunoglobulin-like beta-sandwich structure, which represents a novel fold for an effector of a GTP-binding protein. The interface between the two proteins involves a continuous antiparallel beta-sheet, similar to that found in other effector/G-protein complexes, such as Ras and Rap1A. Specific interactions unique to the RalA.Sec5 complex include Sec5 Thr11 and Arg27, and RalA Glu38, which we show are required for complex formation by isothermal titration calorimetry. Comparison of the structures of GppNHp- and GDP-bound RalA suggests a nucleotide-dependent switch mechanism for Sec5 binding.

PubMed: 12839989
DOI: 10.1093/emboj/cdg329

Experimental method

X-RAY DIFFRACTION (2.1 Å)