Toward Completion of the Human Proteome Parts List: Progress Uncovering Proteins That Are Missing or Have Unknown Function and Developing Analytical Methods

Uncovering Proteins That Are Missing or Have Unknown Function and Developing Analytical Methods F the past 6 years, the Journal of Proteome Research has supported the Human Proteome Organization (HUPO) in dedicating a special issue of the journal to the Chromosomecentric Human Proteome Project (C-HPP); for the past 2 years, it has encompassed the whole HPP with contributions also from the Biology/Disease (B/D)-HPP and the HPP resource pillars. The 32 papers published this month further annotate the human protein parts list or present advances in analytical methods for the identification of proteoforms or new members of the human proteome. This Editorial presents highlights of selected papers that focus on the increasingly difficult task for the C-HPP international teams of identifying the remaining unannotated proteins in the human proteome that lack evidence of existence at the protein level (PE1) but have less direct evidence of their existence (PE2,3,4), the socalled missing proteins (MPs) in neXtProt. In total, 104 MPs have been found that meet the stringent HPP guidelines designed to mitigate against false discovery and incorrect annotation in neXtProt and other public databases (Table 1).