A third interferon-gamma-induced subunit exchange in the 20S proteasome

Eur J Immunol. 1996 Apr;26(4):863-9. doi: 10.1002/eji.1830260421.


The 20S proteasome is a protease complex of functional importance for antigen processing. Two of the 14 proteasome subunits, delta and MB1, can be replaced by the major histocompatibility complex (MHC)-encoded and interferon-gamma (IFN-gamma)-inducible subunits LMP2 and LMP7, respectively. LMP2 and LMP7 alter the cleavage site specificity of the 20S proteasome and are required for the efficient generation of T cell epitopes from a number of viral proteins and for optimal MHC class I cell surface expression. We compared the 20S proteasome subunit pattern from IFN-gamma-induced and non-induced mouse fibroblasts on two-dimensional gels and identified a third subunit exchange by microsequencing: the non-MHC-encoded subunit MECL-1 is induced by IFN-gamma and replaces a sofar barely characterized beta subunit designated 'MC14'. In analogy to LMP2 and LMP7, MECL-1 may be functional in MHC class I-restricted antigen presentation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Antigen Presentation*
  • Cells, Cultured
  • Cysteine Endopeptidases / chemistry
  • Cysteine Endopeptidases / metabolism*
  • Fibroblasts / chemistry
  • Fibroblasts / cytology
  • Fibroblasts / immunology
  • Histocompatibility Antigens Class I / immunology
  • Interferon-gamma / pharmacology*
  • Mice
  • Mice, Inbred BALB C
  • Molecular Sequence Data
  • Multienzyme Complexes / chemistry
  • Multienzyme Complexes / metabolism*
  • Proteasome Endopeptidase Complex
  • Proteins / metabolism*
  • Recombinant Proteins
  • Sequence Alignment
  • Sequence Homology, Amino Acid


  • Histocompatibility Antigens Class I
  • Multienzyme Complexes
  • Proteins
  • Recombinant Proteins
  • LMP-2 protein
  • Interferon-gamma
  • Cysteine Endopeptidases
  • LMP7 protein
  • Proteasome Endopeptidase Complex
  • Psmb10 protein, mouse