Immunoproteasome assembly: cooperative incorporation of interferon gamma (IFN-gamma)-inducible subunits.

Griffin TA, Nandi D, Cruz M, Fehling HJ, Kaer LV, Monaco JJ, Colbert RA
J Exp Med. 1998 187 (1): 97-104

PMID: 9419215 · PMCID: PMC2199179 · DOI:10.1084/jem.187.1.97

LMP2, LMP7, and MECL are interferon gamma-inducible catalytic subunits of vertebrate 20S proteasomes, which can replace constitutive catalytic subunits (delta, X, and Z, respectively) during proteasome biogenesis. We demonstrate that MECL requires LMP2 for efficient incorporation into preproteasomes, and preproteasomes containing LMP2 and MECL require LMP7 for efficient maturation. The latter effect depends on the presequence of LMP7, but not on LMP7 catalytic activity. This cooperative mechanism favors the assembly of homogeneous "immunoproteasomes" containing all three inducible subunits, suggesting that these subunits act in concert to enhance proteasomal generation of major histocompatibility complex class I-binding peptides.

MeSH Terms (16)

Animals Cell Line Cysteine Endopeptidases Enzyme Induction Enzyme Precursors Humans Interferon-gamma Mice Models, Biological Multienzyme Complexes Proteasome Endopeptidase Complex Protein Conformation Protein Processing, Post-Translational Proteins Spleen Transfection

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