This dataset contains a mass spectrometry-based proteomic analysis of RRP12-containing complexes isolated from human HeLa cells. The study was designed to analyze the interactome of the ribosome biogenesis factor RRP12 in the context of RPS19 deficiency, a defect associated with Diamond-Blackfan anemia. Complexes were purified from control and RPS19-knockdown HeLa cells (endogenously expressing GFP-RRP12) using the preribosome extraction and GFP-Trap immunoprecipitation protocol described by Singh et al. (2021; PMID: 34516797). Comparative quantitative analysis of the contents of RRP12-associated proteins, normalized to the amount of RRP12 in each sample, reveals an accumulation of large preribosomal complexes containing SSU-processome ribosome biogenesis factors (RBFs) upon RPS19 depletion. The description of these findings, together with the associated raw data analysis tables, are included in the article entitled "Convergent nuclear proteostasis alterations across ribosomal protein deficiencies" by Gaspar et al. (2026).