Figure 6.

A summary of interactions mediated by XRN1 in 5′–3′ mRNA decay. XRN1 directly interacts with the decapping activator EDC4 via the short linear motif in its very C-terminal end (EDC4-BM, red oval) providing a direct mechanistic link between decapping and subsequent exonucleolytic mRNA decay. XRN1 can also directly interact with the CCR4–NOT deadenylase complex via the low-complexity ‘C-terminal interacting region’ (CIR) and block CAF1-dependent mRNA deadenylation. PatL1 competes with the CCR4–NOT for binding to the CIR and relieves CIR-mediated inhibition of CCR4–NOT catalytic activity in vitro.