5jrt
From Proteopedia
Crystal structure of the human Tankyrase 2 (TNKS2) SAM domain (DH902/924RE)
Structural highlights
Function[TNKS2_HUMAN] Poly-ADP-ribosyltransferase involved in various processes such as Wnt signaling pathway, telomere length and vesicle trafficking. Acts as an activator of the Wnt signaling pathway by mediating poly-ADP-ribosylation of AXIN1 and AXIN2, 2 key components of the beta-catenin destruction complex: poly-ADP-ribosylated target proteins are recognized by RNF146, which mediates their ubiquitination and subsequent degradation. Also mediates poly-ADP-ribosylation of BLZF1 and CASC3, followed by recruitment of RNF146 and subsequent ubiquitination. Mediates poly-ADP-ribosylation of TERF1, thereby contributing to the regulation of telomere length. May also regulate vesicle trafficking and modulate the subcellular distribution of SLC2A4/GLUT4-vesicles.[1] [2] [3] [4] Publication Abstract from PubMedThe poly(ADP-ribose) polymerase (PARP) Tankyrase (TNKS and TNKS2) is paramount to Wnt-beta-catenin signaling and a promising therapeutic target in Wnt-dependent cancers. The pool of active beta-catenin is normally limited by destruction complexes, whose assembly depends on the polymeric master scaffolding protein AXIN. Tankyrase, which poly(ADP-ribosyl)ates and thereby destabilizes AXIN, also can polymerize, but the relevance of these polymers has remained unclear. We report crystal structures of the polymerizing TNKS and TNKS2 sterile alpha motif (SAM) domains, revealing versatile head-to-tail interactions. Biochemical studies informed by these structures demonstrate that polymerization is required for Tankyrase to drive beta-catenin-dependent transcription. We show that the polymeric state supports PARP activity and allows Tankyrase to effectively access destruction complexes through enabling avidity-dependent AXIN binding. This study provides an example for regulated signal transduction in non-membrane-enclosed compartments (signalosomes), and it points to novel potential strategies to inhibit Tankyrase function in oncogenic Wnt signaling. Tankyrase Requires SAM Domain-Dependent Polymerization to Support Wnt-beta-Catenin Signaling.,Mariotti L, Templeton CM, Ranes M, Paracuellos P, Cronin N, Beuron F, Morris E, Guettler S Mol Cell. 2016 Aug 4;63(3):498-513. doi: 10.1016/j.molcel.2016.06.019. PMID:27494558[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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