UBR5 interacts with spliceosome components. (A) Western blot of immunoprecipitation of UBR5 from MINO and JEKO1 MCL cell line used for MS analysis. MS experiment was performed in duplicate. (B) Gene ontology analysis of immunoprecipitated proteins. (C) Venn diagram showing the significant overlap of proteins identified in the TMT labeled UBR5^WT and Ubr5^ΔHECT MS and those identified in the UBR5 endogenous immunoprecipitation MS. (D) Venn diagram showing overlap of the proteins significantly upregulated (≥1.3, P < .05) in the Ubr5^ΔHECT samples and those identified in the UBR5 endogenous IP. (E) Spliceosome-associated proteins found in endogenous immunoprecipitation and/or upregulated in spleen B220⁺ cells. (F) Bar graphs of relative MFI of cell surface markers of B220⁺ splenocytes (N = 6). (G) Representative immunohistochemistry staining of UBR5 in Ubr5^WT and Ubr5^ΔHECT spleens (N = 3). **P < .01, ****P < .0001.