The original version of Fig. 2B contained elements from Fig. 1 of Udeshi, N.D., Mertins, P., Svinkina, T., and Carr, S.A. (2013) Large-scale identification of ubiquitination sites by mass spectrometry. Nat. Protoc. 8, 1950-60. An updated schematic for Fig. 2B (created using Bio- Render.com) is provided below. (Figure Presented).