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Science 8 September 2006:
Vol. 313. no. 5792, p. 1360
DOI: 10.1126/science.313.5792.1360j
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Recently, a role for the proteasome was discovered in splicing together noncontiguous peptides into effective antigens. Warren et al. (p. 1444; see the Perspective by Shastri) identified an antigenic peptide that corresponds to a minor histocompatibility antigen that is expressed on leukemic cells. The antigen was also created in the proteasome by splicing of two noncontiguous fragments of the parental protein, but the two fragments were spliced in the reverse order to that in which they occur in the parent protein. Splicing of these reordered peptide fragments occurred by transpeptidation involving an acyl-enzyme intermediate. This mode of production of antigenic peptides expands the diversity of antigenic peptides presented on class I molecules and is potentially relevant for T cell recognition of tumors and pathogens.




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