Proteome catalogue reveals 193 unknown proteins

A proteome catalogue has revealed 193 novel proteins in regions of the genome not predicted to code for proteins, suggesting the human genome is more complex than previously thought. Using a total of 30 different human tissues, an international team of researchers has identified proteins encoded by 17,294 genes – about 84% of all the genes in the human genome predicted to encode proteins, including 193 human proteins never known to exist. “You can think of the human body as a huge library where each protein is a book,” said Akhilesh Pandey from Johns Hopkins University. “The difficulty is that we don’t have a comprehensive catalogue that gives us the titles of the available books and where to find them. We think we now have a good first draft of that comprehensive catalogue.” The catalogue should provide an important resource for biological research and medical diagnostics, possibly even more useful than a catalogue of human genes since it provides location details and the instructions for making proteins. The research team took samples of 30 tissues and extracted their proteins before using enzymes to cut them into peptides. They then ran the peptides through a series of instruments to deduce their identity and measure their relative abundance. “By generating a comprehensive human protein dataset, we have made it easier for other researchers to identify the proteins in their experiments,” said Pandey. “We believe our data will become the gold standard in the field, especially because they were all generated using uniform methods and analysis, and state-of-the-art machines.” Among those proteins whose data patterns have been revealed for the first time are many scientists didn’t think existed. “This was the most exciting part of this study, finding further complexities in the genome,” said Pandey. “The fact that 193 of the proteins came from DNA sequences predicted to be noncoding means that we don’t fully understand how cells read DNA, because clearly those sequences do code for proteins.” Pandey believes that because of this complexity, the catalogue may never be complete, but that this work, published in Nature, provides a solid foundation for other to build on. A draft map of the human proteome