The Human Protein Atlas and tissue proteomics
The Human Protein Atlas charted where the proteins encoded by human genes are expressed across tissues, turning the proteome into an open, browsable map for research.
What the study found
In 2015, researchers published a tissue-based map of the human proteome in Science — the Human Protein Atlas. Using antibody staining and transcriptomics across dozens of human tissues and organs, they charted where the proteins encoded by human genes are expressed, from ubiquitous "housekeeping" proteins found almost everywhere to those restricted to a single organ. All of the data were made freely available online for any researcher to browse.
Why it matters
Genes are the same in every cell, but which proteins are actually made, and where, is what defines a tissue's job and how disease arises. A comprehensive expression map helps researchers shortlist candidate drug targets, interpret what a disease-linked gene might do, and flag where a drug aimed at one organ might hit proteins in another. Drug developers increasingly check where a target protein is expressed before pursuing it, to anticipate off-target effects in healthy tissue.
Analysis — the pattern
Placed alongside tools like AlphaFold (this is analysis): structure prediction tells you a protein's shape, while an expression atlas tells you where and how much of it appears. Together they move protein research from studying one protein at a time toward systems-level maps. An active, still-maturing direction is single-cell and spatial proteomics, which resolves expression cell by cell rather than tissue by tissue.
What is still uncertain
Antibody-based localization has limits and needs careful validation, and expression is not the same as function. The atlas is a reference resource, not a diagnosis, and its coverage and accuracy continue to improve as newer methods are added.