Figure 4.

Proteomic profiling of ribosome peaks. HeLa whole cell lysate was applied to a 5 to 40% sucrose gradient and subjected to ultracentrifugation to separate ribosomal subunits. Samples were fractionated, and the absorbance at 254 nm was recorded. Fractions specific to the four peaks of interest from a representative control sample were subject to in-gel digestion and mass spectrometry analysis (Table S1). Peaks 1 and 2 were unambiguously confirmed as the 40S and 60S ribosomal subunits, respectively, as indicated by the core proteins identified. The 80S split peak (peaks 3 and 4) was confirmed as the mature 80S ribosome, containing 40S and 60S proteins with a notably higher abundance in peak 4, consistent with the presence of an additional mature ribosome (disome).