Investigators have analyzed the Human Protein Atlas to provide detailed information on the proteins expressed in the body—for example, identifying those proteins linked to cancer, estimating the number that are present in the bloodstream, and determining those that are targets for approved drugs on the market (Uhlén M et al. Science. doi:10.1126/science.1260419 [published online January 23, 2015]).
By applying RNA expression analyses and antibody-based identification techniques across 32 human tissues and organs, a team led by Swedish researchers estimated that 44% of proteins are active in all tissues, many with “housekeeping” functions related to cell growth and metabolism. The testes have the most tissue-enriched proteins, while the second largest number of enriched proteins is the brain.
Hampton T. Analysis Provides Map of Protein Expression in Human Tissues. JAMA. 2015;313(9):885. doi:10.1001/jama.2015.0691