XTBD is a family of eukaryotic proteins that act as an XRN2-binding module. XRN2 is an essential exoribonuclease in eukaryotes that processes and degrades a number of different substrates. XTBD is found on a number of different proteins to link them to XRN, such as PAXT-1 [1].

1: PAXT-1 Promotes XRN2 Activity by Stabilizing It through a Conserved Domain. Miki TS, Richter H, Ruegger S, Grosshans H; Mol Cell. 2014;53:351-360. PMID:24462208