Endogenous expression of alternative proteins in cultured cells.

(A) Alternative proteins expression was analyzed by LC-MS/MS in HeLa cells, and a schematic distribution of AltORFs in absolute numbers is shown. There were a total of 129 identified alternative proteins (indicated in the center). (B) Average peptide intensity plot of both the reference and alternative proteins that were co-expressed from 42 genes. (C) Same as (A) with colon cell lines. (D) Venn diagram showing the number of alternative proteins identified in HeLa cells and colon cell lines. The overlap identifies a common list of 14 alternative proteins.