Bioinformatic analysis of functional differences between the immunoproteasome and the constitutive proteasome

Can Kesmir, V. van Noort, R.J. de Boer, P. Hogeweg

    Research output: Contribution to journalJournal articleResearchpeer-review


    Intracellular proteins are degraded largely by proteasomes. In cells stimulated with gamma interferon , the active proteasome subunits are replaced by 'immuno' subunits that form immunoproteasomes. Phylogenetic analysis of the immunosubunits has revealed that they evolve faster than their constitutive counterparts. This suggests that the immunoproteasome has evolved a function that differs from that of the constitutive proteasome. Accumulating experimental degradation data demonstrate, indeed, that the specificity of the immunoproteasome and the constitutive proteasome differs. However, it has not yet been quantified how different the specificity of two forms of the proteasome are. The main question, which still lacks direct evidence, is whether the immunoproteasome generates more MHC ligands. Here we use bioinformatics tools to quantify these differences and show that the immunoproteasome is a more specific enzyme than the constitutive proteasome. Additionally, we predict the degradation of pathogen proteomes and find that the immunoproteasome generates peptides that are better ligands for MHC binding than peptides generated by the constitutive proteasome. Thus, our analysis provides evidence that the immunoproteasome has co-evolved with the major histocompatibility complex to optimize antigen presentation in vertebrate cells.
    Original languageEnglish
    Issue number7
    Pages (from-to)437-449
    Publication statusPublished - 2003


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