DNA sequence data offer tremendous insight into the biology of an organism, but they are not the whole story. In recent years, molecular biologists have turned their attention to the analysis of the protein content of cells. Their ultimate goal is to determine the proteome: the complete set of proteins found in a given cell. The study of the proteome is termed proteomics.

Plans are under way to identify and characterize all proteins in the human body, an effort that has been called the Human Proteome Project. The project will catalog the proteins present in each cell type, where each protein is located within the cell, and with which other proteins each interacts. Many researchers think that this information will be of immense benefit in identifying drug targets, understanding the biological basis of disease, and understanding the molecular basis of many biological processes.