Tagging Peptides Enables C-Terminomics

Many proteins are activated by a quick snip at their ends by protease enzymes. However, the bulk of what is known about protease activity involves proteins that are cleaved and then sequenced from the N-terminus. Until now, there hasn’t been a robust, inexpensive procedure that enables unbiased fishing for proteins that get activated by C-terminal cleavage in complex protein mixtures, such as in cells. A solution to this problem comes from Christopher M. Overall of the University of British Columbia, Vancouver, and coworkers who are reporting a method for quantitative, proteome-wide analysis of proteins that get cleaved at the C-terminus as part of their role in a cell (Nat. Methods, DOI: 10.1038/nmeth.1467). The team discovered a set of protection and proteolytic steps that results in a tagged C-terminus peptide that is separated from the rest of the protein. Although a handful of biochemical processes are known to be activated by C-terminal cleavage—including the processing of peptide hormones—the researchers believe many more such processes will be found now that the new strategy is available.