Vault Interactome in WT and PARP4-Depleted A549 Cells

We sought to determine whether the vault complex component Poly (ADP-ribose) Polymerase 4 (PARP4) would impact the identity or relative enrichment of proteins that interacted with the vault. We conducted co-immunoprecipitation (co-IP) experiments targeting the human major vault protein (MVP) using a synthetic antigen binding reagent (sAB) generated for this study. Experimental co-IP's were conducted by adding the anti-MVP sAB (called VM1) to WT A549 cells and to cells from which PARP4 had been depleted using CRISPR/Cas9. To control for background, we concurrently processed samples to which we had added an anti-GFP sAB (called H6) that was highly similar to our anti-MVP reagent but was not specific for any human proteins. PARP4, as well as a number of other proteins, were significantly enriched in the experimental co-IP from the WT versus PARP4 KO cells. Overall, we identified 34 hits that were either unique to or differentially enriched in the WT cell experimental co-IP, 16 hits that were unique to the PARP4 KO experimental co-IP, and 18 "shared" hits that were present in each experimental co-IP dataset without significant differential enrichment in either.