6kyk
From Proteopedia
Crystal structure of Shank3 NTD-ANK mutant in complex with Rap1
Structural highlights
Function[SHAN3_MOUSE] Major scaffold postsynaptic density protein which interacts with multiple proteins and complexes to orchestrate the dendritic spine and synapse formation, maturation and maintenance. Interconnects receptors of the postsynaptic membrane including NMDA-type and metabotropic glutamate receptors via complexes with GKAP/PSD-95 and HOMER, respectively, and the actin-based cytoskeleton. Plays a role in the structural and functional organization of the dendritic spine and synaptic junction through the interaction with Arp2/3 and WAVE1 complex as well as the promotion of the F-actin clusters. By way of this control of actin dynamics, participates in the regulation of developing neurons growth cone motility and the NMDA receptor-signaling. Also modulates GRIA1 exocytosis and GRM5/MGLUR5 expression and signaling to control the AMPA and metabotropic glutamate receptor-mediated synaptic transmission and plasticity. May be required at an early stage of synapse formation and be inhibited by IGF1 to promote synapse maturation.[1] [2] [3] [4] [RAP1B_HUMAN] GTP-binding protein that possesses intrinsic GTPase activity. Contributes to the polarizing activity of KRIT1 and CDH5 in the establishment and maintenance of correct endothelial cell polarity and vascular lumen. Required for the localization of phosphorylated PRKCZ, PARD3 and TIAM1 to the cell junction.[5] [6] Publication Abstract from PubMedShank1/2/3, major scaffold proteins in excitatory synapses, are frequently mutated in patients with psychiatric disorders. Although the Shank N-terminal domain and ankyrin repeats domain tandem (NTD-ANK) is known to bind to Ras and Rap1, the molecular mechanism underlying and functional significance of the bindings in synapses are unknown. Here, we demonstrate that Shank3 NTD-ANK specifically binds to the guanosine triphosphate (GTP)-bound form of HRas and Rap1. In addition to the canonical site mediated by the Ras-association domain and common to both GTPases, Shank3 contains an unconventional Rap1 binding site formed by NTD and ANK together. Binding of Shank3 to the GTP-loaded Rap1 slows down its GTP hydrolysis by SynGAP. We further show that the interactions between Shank3 and HRas/Rap1 at excitatory synapses are promoted by synaptic activation. Thus, Shank3 may be able to modulate signaling of the Ras family proteins via directly binding to and stabilizing the GTP-bound form of the enzymes. Shank3 Binds to and Stabilizes the Active Form of Rap1 and HRas GTPases via Its NTD-ANK Tandem with Distinct Mechanisms.,Cai Q, Hosokawa T, Zeng M, Hayashi Y, Zhang M Structure. 2019 Dec 17. pii: S0969-2126(19)30436-8. doi:, 10.1016/j.str.2019.11.018. PMID:31879129[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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