PROSITE documentation PDOC51827
XRN2-binding (XTBD) domain profile


XRN2 is an essential eukaryotic exoribonuclease that processes and degrades various substrates. The ~80-residue XRN2-binding domain (XTBD) constitutes an XRN2-binding module that is employed by different metazoan proteins to link to XRN2 [1,2]:

  • Caenorhabditis elegans Partner of Xrn-Two protein 1, or PAXT-1 for short. Plays a role in maintenance of steady-state concentration and turnover of microRNAs (miRNA) by degradation of mature miRNA in complex with the exoribonuclease XRN-2.
  • Mammalian CDKN2A-interacting protein (CDKN2AIP) or Collaborator of ARF (CARF). Regulates DNA damage response in a dose-dependent manner through a number of signaling pathways involved in cell proliferation, apoptosis and senescence.
  • Mammalian CDKN2AIP N-terminal-like protein (CDKN2AIPNL).

The XTBD domain folds into a globular four-helix bundle (H1-H4) connected by three loops (L1-L3) (see <PDB:5FIR>). H1-H3 form an antiparallel helical array and H4 folds back on top of H2 and H3 at an 90 degrees angle. The four-helical bundle is mainly stabilized by hydrophobic helix-helix interactions together with additional polar interactions between side chains located on neighboring helices. The four-helix bundle of XTBD represents a structurally unique arrangement for XRN2 binding [2].

The profile we developed covers the entire XTBD domain.

Last update:

January 2017 / First entry.


Technical section

PROSITE method (with tools and information) covered by this documentation:

XTBD, PS51827; XRN2-binding (XTBD) domain profile  (MATRIX)


1AuthorsMiki T.S. Richter H. Rueegger S. Grosshans H.
TitlePAXT-1 promotes XRN2 activity by stabilizing it through a conserved domain.
SourceMol. Cell 53:351-360(2014).
PubMed ID24462208

2AuthorsRichter H. Katic I. Gut H. Grosshans H.
TitleStructural basis and function of XRN2 binding by XTB domains.
SourceNat. Struct. Mol. Biol. 23:164-171(2016).
PubMed ID26779609

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