4dxa
From Proteopedia
Co-crystal structure of Rap1 in complex with KRIT1
Structural highlights
Disease[KRIT1_HUMAN] Hereditary cerebral cavernous malformation. Cerebral cavernous malformations 1 (CCM1) [MIM:116860]: A congenital vascular anomaly of the central nervous system that can result in hemorrhagic stroke, seizures, recurrent headaches, and focal neurologic deficits. The lesions are characterized by grossly enlarged blood vessels consisting of a single layer of endothelium and without any intervening neural tissue, ranging in diameter from a few millimeters to several centimeters. Note=The disease is caused by mutations affecting the gene represented in this entry.[1] Function[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.[2] [3] [KRIT1_HUMAN] Component of the CCM signaling pathway which is a crucial regulator of heart and vessel formation and integrity (By similarity). Negative regulator of angiogenesis. Inhibits endothelial proliferation, apoptosis, migration, lumen formation and sprouting angiogenesis in primary endothelial cells. Promotes AKT phosphorylation in a NOTCH-dependent and independent manner, and inhibits EKR1/2 phosphorylation indirectly through activation of the DELTA-NOTCH cascade. Acts in concert with CDH5 to establish and maintain correct endothelial cell polarity and vascular lumen and these effects are mediated by recruitment and activation of the Par polarity complex and RAP1B. Required for the localization of phosphorylated PRKCZ, PARD3, TIAM1 and RAP1B to the cell junction, and cell junction stabilization. Plays a role in integrin signaling via its interaction with ITGB1BP1; this prevents the interaction between ITGB1 and ITGB1BP1. Plays an important role in the maintenance of the intracellular reactive oxygen species (ROS) homeostasis to prevent oxidative cellular damage. Regulates the homeostasis of intracellular ROS through an antioxidant pathway involving FOXO1 and SOD2. Facilitates the down-regulation of cyclin-D1 (CCND1) levels required for cell transition from proliferative growth to quiescence by preventing the accumulation of intracellular ROS through the modulation of FOXO1 and SOD2 levels.[4] [5] [6] [7] [REFERENCE:17] Publication Abstract from PubMedCerebral cavernous malformations (CCM) affect 0.1-0.5% of the population resulting in leaky vasculature and severe neurological defects. KRIT1 (Krev interaction trapped-1) mutations associate with ~40% of familial CCM. KRIT1 is an effector of Ras-related protein 1 (Rap1) GTPase. Rap1 relocalizes KRIT1 from microtubules to cell membranes to impact integrin activation, potentially important for CCM pathology. We report the 1.95A co-crystal structure of KRIT1 FERM domain in complex with Rap1. Rap1-KRIT1 interaction encompasses an extended surface, including Rap1 Switch I and II and KRIT1 FERM F1 and F2 lobes. Rap1 binds KRIT1-F1 lobe using a GTPase-ubiquitin-like fold interaction, but binds KRIT1-F2 lobe by a novel interaction. Point mutagenesis confirms the interaction. High similarity between KRIT1-F2/F3 and Talin is revealed. Additionally, the mechanism for FERM domains acting as GTPase effectors is suggested. Finally, structure-based alignment of each lobe suggests classification of FERM domains as ERM-like and TMFK-like (Talin-Myosin-FAK-Krit-like) and that FERM lobes resemble domain modules. Structural basis for the small G-protein-effector interaction of Ras-related protein 1 (Rap1) and the adaptor protein Krev interaction trapped 1 (KRIT1).,Li X, Zhang R, Draheim KM, Liu W, Calderwood DA, Boggon TJ J Biol Chem. 2012 May 10. PMID:22577140[8] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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