The identification of ubiquitination sites of IBTK by shotgun proteomics

Previous study reported that eIF4A1 protein stability is subject to control by the ubiquitin-proteasome pathway, and deubiquitinase USP9X elevated eIF4A1 protein level by promoting eIF4A1 deubiquitination. However, the E3 ubiquitin ligases responsible for eIF4A1 proteolysis is not determined. Our research suggested that IBTK mediated non-degradative ubiquitination of eIF4A1, thus probable ubiquitination sites of eIF4A1 were identified by MS analysis.