29 May 2014
The first databases of the human protein repertoire or proteome have been published; the proteome represents all the possible proteins that can be produced.
The first complete human genome sequence was widely lauded as the crucial blueprint for life, since the genome contains all the information needed for the creation and maintenance of a human being, encoded in DNA.
Whilst the production of the first human genome remains a monumental feat of international scientific ingenuity, cooperation and sheer hard graft, it was in fact only the beginning. The genome contains many more complexities to unravel and decipher. It soon became evident that only a tiny proportion of the DNA specified the production of proteins in the form of around 20,000 genes or protein-coding stretches of DNA. The importance of understanding not only the genome but also the proteome became a focus for biomedical research.
Now two independent research groups have published details of the first two human proteomes — showing the repertoire of proteins actually present in human cells and tissues, determined by mass spectometry. One proteome map is from researchers in Germany and the other proteome map is from a collaboration between groups in the US and India; both are published in the journal Nature this week and on open access databases.
The findings include surprises; some proteins are produced from DNA regions thought to be non-coding, both ancient ‘pseudogenes’ and other stretches not thought to be any form of gene sequence. Other presumed functional genes were not found to be producing corresponding proteins. Comparisons of the proteome maps are likely to be useful, since they are not identical and are built on different approaches.
Naturally, these proteomes are not comprehensive — they are drawn from thirty different tissues, adult and fetal, as well as cell lines and body fluids, but there are many more types of specialised cells, and protein expression can vary over time and in response to different conditions as well as between cells. However, the assertion of one paper that the map ‘will complement available human genome and transcriptome data to accelerate biomedical research in health and disease’ seems a fair one.