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Crystal structure of ARC4 from human Tankyrase 2 in complex with phosphorylated peptide from human MDC1
Structural highlights
FunctionTNKS2_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 ADP-ribosyltransferase tankyrase (with two paralogues, TNKS and TNKS2) plays pivotal roles in diverse cellular processes that encompass signal transduction, including Wnt/beta-catenin, Hippo and toll-like receptor (TLR) signalling, mitotic spindle assembly, glucose homeostasis and telomere maintenance, among many other functions. Tankyrase recruits its effectors (substrates and binders) via a degenerate tankyrase-binding motif (TBM) and exerts its activities by subsequent substrate ADP-ribosylation and/or scaffolding. Variants of the TBM, found in diverse proteins, engage the ankyrin repeat cluster (ARC) domains of tankyrase. Yet, whether effector recruitment to tankyrase can be regulated has remained unknown. In this study, we propose that phosphorylation at position eight of the TBM enhances the affinity of effectors for the ARC domains of tankyrase. Using isolated TBM peptides, we demonstrate that phosphorylation of serine, but not tyrosine, strengthens ARC binding by up to an order of magnitude. Interrogation of proteome-wide phosphorylation data reveals that phosphorylation at position eight in the TBM is enriched in proteins that support centrosome function/localization. Our findings suggest that TBM phosphorylation may serve as an effector-specific mechanism for tankyrase recruitment/retention, providing an additional layer of regulation to control tankyrase. Phosphorylation as a candidate regulatory mechanism for effector recruitment to tankyrase.,Broadway BJ, Pollock K, Cronin N, Rottapel R, Sicheri F, Guettler S R Soc Open Sci. 2025 Oct 15;12(10):250824. doi: 10.1098/rsos.250824. eCollection , 2025 Oct. PMID:41103766[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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