Fig. 3. High confidence co-co assembly proteins are enriched in homo-oligomers.

A) Examples of gene-specific disome over monosome enrichment profiles (DiSP data, in the background, n = 2) and the corresponding fitting (solid lines) for each of the three possible shapes of DiSP enrichments. The single sigmoid agrees with nascent chain-connected ribosomes that terminate translation simultaneously, either by co-co assembly in trans if the mRNA segments translated by both ribosomes after co-co assembly have similar lengths, or in cis, with ribosomes that closely follow each other on the same mRNA (top). The double sigmoid agrees with co-co assembly involving two ribosomes that do not terminate at the same time; this may occur in trans if the mRNA segments translated by both ribosomes after co-co assembly have different lengths, or in cis, if the leading ribosome is distant from the trailing one (middle). Flat enrichment profiles indicate that nascent proteins do not co-co assemble.

B) Metagene profiles of all high confidence candidates aligned to assembly onset (top). Footprint density in the monosome fraction and the total translatome are shown (n = 2). Gene-specific quantification of the efficiency of co-co assembly, calculated as the relative depletion of footprint density in monosome compared to total translatome after assembly onset (bottom). The median monosome depletion for each replicate is indicated by blue dashed lines.

C) Frequency enrichment of annotated subunits of protein complexes in high and low confidence lists compared to the whole proteome (absolute and relative numbers are provided in Table S2) (33). The number of genes included in each assembly class is indicated in the bar plot. The p-values were calculated using an enrichment test adjusted for expression bias (33, 34).

D) Distribution of residues forming the inter-subunit interface of protein complexes determined from available crystal structures. The position of interface residues on the proteins' primary sequence is aligned to assembly onset of high confidence homomers (left) or heteromers (right).