Stable binding of the herpes simplex virus ICP47 protein to the peptide binding site of TAP

Roman Tomazin, Ann B. Hill, Pieter Jugovic, Ian York, Peter Van Endert, Hidde L. Ploegh, David W. Andrews, David C. Johnson

Research output: Contribution to journalArticlepeer-review

224 Scopus citations


The herpes simplex virus (HSV) ICP47 protein inhibits the MHC class I antigen presentation pathway by inhibiting the transporter associated with antigen presentation (TAP) which translocates peptides across the endoplasmic reticulum membrane. At present, ICP47 is the only inhibitor of TAP. Here, we show that ICP47 produced in bacteria can block human, but not mouse, TAP, and that heat denaturation of ICP47 has no effect on its ability to block TAP. ICP47 inhibited peptide binding to TAP without affecting ATP binding, consistent, with previous observations that the peptide binding and ATP binding sites of TAP are distinct. ICP47 bound to TAP with a higher affinity (KD ~5 x 10-8 M) than did peptides, and ICP47 did not dissociate from TAP. ICP47 was not transported by TAP and remained sensitive to proteases added from the cytosolic surface of the membrane. Peptides acted as competitive inhibitors of ICP47 binding to TAP, and this inhibition required a 100- to 1000-fold molar excess of peptide. These results demonstrate that ICP47 binds to a site which includes the peptide binding domain of TAP and remains bound to this site in a stable fashion.

Original languageEnglish (US)
Pages (from-to)3256-3266
Number of pages11
JournalEMBO Journal
Issue number13
StatePublished - Jul 1 1996


  • Herpes simplex virus
  • ICP47
  • Peptide binding site
  • TAP

ASJC Scopus subject areas

  • General Neuroscience
  • Molecular Biology
  • General Biochemistry, Genetics and Molecular Biology
  • General Immunology and Microbiology


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