Characterization of an incompletely assembled major histocompatibility class I molecule (H-2K(b)) associated with unusually long peptides: Implications for antigen processing and presentation

S. Joyce, K. Kuzushima, G. Kepecs, R. H. Angeletti, S. G. Nathenson

Research output: Contribution to journalArticle

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We have identified two forms of a major histocompatibility complex (MHC) class I molecule, H-2K(b), distinguishable by specific antibodies through a study of a genetically engineered mouse cell line that overexpresses these molecules. One form, a complex associated with β2-microglobulin (native, β2m+ class I), is detectable by conformation-dependent antibodies. The other form, which remains after preclearing cell lysates of native class I, is only poorly, if at all, associated with β2-microglobulin (β2m- class I) and is detectable by an antiserum against the cytoplasmic tail region of H-2K molecules. Both forms are also present in normal cell lines. The affinity-purified native class I molecules bind short peptides (8 or 9 residues) and assemble tightly with β2-microglobulin. In striking contrast, the β2m- class I molecules bind peptides that are longer (>15 residues) than those bound to native class I molecules. This finding is consistent with the recent evidence that peptides longer than 8-10 amino acid residues are transported into the endoplasmic reticulum and suggests the possibility of a control step for peptide presentation by MHC in which the incompletely processed peptides bind to the heavy chain and a selected fraction undergoes final processing and presentation on the cell surface.

Original languageEnglish (US)
Pages (from-to)4145-4149
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number10
Publication statusPublished - Jan 1 1994



  • peptides
  • β-microglobulin
  • β-microglobulin class I
  • β-microglobulin class I

ASJC Scopus subject areas

  • General

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