Ultra-deep proteome and transcriptome mapping of a human cancer cell line

While the number and identity of proteins expressed in a single human cell type is currently unknown, this fundamental question can be addressed by advanced mass spectrometry (MS)-based proteomics. On-line liquid chromatography coupled to high resolution MS and MS/MS yielded more than 150,000 unique peptides that identified more than 10,000 different human proteins encoded by more than 9,000 human genes. Deep transcriptome sequencing revealed transcripts for nearly all detected proteins. We show that the abundances of more than 90% of proteins and transcripts fall within a 10,000-fold range, and allocate the proteome to different compartments, complexes and functions. Comparisons of the proteome and the transcriptome, and analysis of protein complex databases and GO categories, suggest that we achieved almost complete coverage of the functional transcriptome and the proteome of a single cell type.