Stress protein (hsp73)-mediated, TAP-independent processing of endogenous, truncated SV40 large T antigen for Db-restricted peptide presentation

Eur J Immunol. 1997 Aug;27(8):2016-23. doi: 10.1002/eji.1830270828.


Transporter associated with antigen processing (TAP)-competent and TAP-deficient cell lines were transfected with expression plasmids encoding either the wild-type (wt) large tumor antigen (T-Ag) of SV40, or a truncated cytoplasmic variant (cT-Ag) of this viral protein. Stable expression of comparable levels of both forms of the viral protein was observed in different transfectants. The truncated cT-Ag variant, but not the wtT-Ag was stably associated with the constitutively expressed, cytosolic heat shock protein (hsp)73 chaperone. Two Db-binding peptides and one Kb-binding peptide of T-Ag were presented to cytotoxic T lymphocyte lines (CTLL) by TAP-competent transfectants expressing either wtT-Ag or cT-Ag. TAP-deficient transfectants expressing the wtT-Ag did not present any of these epitopes to CTLL. In contrast, TAP-deficient transfectants expressing the truncated hsp73-associated cT-Ag, presented the two Db-binding epitopes, but not the Kb-binding T-Ag epitope to CTLL. Regurgitation of peptides by transfectants was not detectable. The described data indicate that a pool of post-Golgi Db molecules is available for 2-3 h in TAP-deficient transfectants for loading with peptides released during endolysosomal processing of hsp73-associated, endogenous antigen.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigen Presentation*
  • Antigens, Polyomavirus Transforming / genetics
  • Antigens, Polyomavirus Transforming / metabolism*
  • Carrier Proteins / metabolism*
  • Cell Line
  • Cell Membrane / immunology
  • Gene Expression
  • H-2 Antigens / metabolism*
  • HSC70 Heat-Shock Proteins
  • HSP70 Heat-Shock Proteins*
  • Histocompatibility Antigen H-2D
  • Mice
  • T-Lymphocytes, Cytotoxic / immunology
  • Transfection


  • Antigens, Polyomavirus Transforming
  • Carrier Proteins
  • H-2 Antigens
  • H-2Kb protein, mouse
  • HSC70 Heat-Shock Proteins
  • HSP70 Heat-Shock Proteins
  • Histocompatibility Antigen H-2D
  • Hspa8 protein, mouse