3al8

Plexin A2 / Semaphorin 6A complexPlexin A2 / Semaphorin 6A complex

Structural highlights 3al8 is a 2 chain structure with sequence from Lk3 transgenic mice. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: , , Related: 3al9 Gene: Sema6a, Semaq (LK3 transgenic mice), Plxna2, Kiaa0463 (LK3 transgenic mice) Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [SEM6A_MOUSE] Cell surface receptor for PLXNA2 that plays an important role in cell-cell signaling. Required for normal granule cell migration in the developing cerebellum. Promotes reorganization of the actin cytoskeleton and plays an important role in axon guidance in the developing central nervous system. Can act as repulsive axon guidance cue. Has repulsive action towards migrating granular neurons. May play a role in channeling sympathetic axons into the sympathetic chains and controlling the temporal sequence of sympathetic target innervation. [PLXA2_MOUSE] Coreceptor for SEMA3A and SEMA6A. Necessary for signaling by SEMA6A and class 3 semaphorins and subsequent remodeling of the cytoskeleton. Plays a role in axon guidance, invasive growth and cell migration. Class 3 semaphorins bind to a complex composed of a neuropilin and a plexin. The plexin modulates the affinity of the complex for specific semaphorins, and its cytoplasmic domain is required for the activation of down-stream signaling events in the cytoplasm. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed Semaphorins and their receptor plexins constitute a pleiotropic cell-signalling system that is used in a wide variety of biological processes, and both protein families have been implicated in numerous human diseases. The binding of soluble or membrane-anchored semaphorins to the membrane-distal region of the plexin ectodomain activates plexin's intrinsic GTPase-activating protein (GAP) at the cytoplasmic region, ultimately modulating cellular adhesion behaviour. However, the structural mechanism underlying the receptor activation remains largely unknown. Here we report the crystal structures of the semaphorin 6A (Sema6A) receptor-binding fragment and the plexin A2 (PlxnA2) ligand-binding fragment in both their pre-signalling (that is, before binding) and signalling (after complex formation) states. Before binding, the Sema6A ectodomain was in the expected 'face-to-face' homodimer arrangement, similar to that adopted by Sema3A and Sema4D, whereas PlxnA2 was in an unexpected 'head-on' homodimer arrangement. In contrast, the structure of the Sema6A-PlxnA2 signalling complex revealed a 2:2 heterotetramer in which the two PlxnA2 monomers dissociated from one another and docked onto the top face of the Sema6A homodimer using the same interface as the head-on homodimer, indicating that plexins undergo 'partner exchange'. Cell-based activity measurements using mutant ligands/receptors confirmed that the Sema6A face-to-face dimer arrangement is physiologically relevant and is maintained throughout signalling events. Thus, homodimer-to-heterodimer transitions of cell-surface plexin that result in a specific orientation of its molecular axis relative to the membrane may constitute the structural mechanism by which the ligand-binding 'signal' is transmitted to the cytoplasmic region, inducing GAP domain rearrangements and activation. Structural basis for semaphorin signalling through the plexin receptor.,Nogi T, Yasui N, Mihara E, Matsunaga Y, Noda M, Yamashita N, Toyofuku T, Uchiyama S, Goshima Y, Kumanogoh A, Takagi J Nature. 2010 Sep 29. PMID:20881961 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Plexin Semaphorin

spinqualitylabelsall models 3al8, resolution 3.60Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image