During co-translational translocation at the endoplasmic reticulum (ER), ribosomes can stall and become covalently modified with the ubiquitin-like protein UFM1 on the 60S ribosomal subunit RPL26 (uL24). This process, known as UFMylation, is mediated by the UFM1 Ribosome E3 Ligase (UREL) complex, comprised of UFL1, UFBP1, and CDK5RAP3. However, the functional consequences of UFMylation and catalytic mechanisms of UREL are unknown. Here, we present crosslinking-mass spectrometry (XL-MS) data of UREL bound to 60S ribosomes.