Immunology: Protein surgery.

This article comments on a article by K.-i. Hanada and colleagues titled, "Immune Recognition of a Human Renal Cancer Antigen Through Post-Translational Protein Splicing," published in the January 15, 2004 issue of the periodical "Nature." The results of the paper by Hanada and colleagues show that by slicing a protein into pieces, stitching different portions together, and then cutting out strings of nine sequential amino acids from the melded pieces, cells can manufacture entirely new sets of peptides from the original protein. On the question that how could a cell make such a cut-and-paste peptide, the authors first wondered whether RNA splicing was the answer. Similar processes of protein surgery have been observed before, in single-celled organisms and some plants.