The coreceptor CD8αβ can greatly promote activation of T cells by strengthening T-cell receptor (TCR) binding to cognate peptide-MHC complexes (pMHC) on antigen presenting cells and by bringing p56Lck to TCR/CD3. Here, we demonstrate that CD8 can also bind to pMHC on the T cell (in cis) and that this inhibits their activation. Using molecular modeling, fluorescence resonance energy transfer experiments on living cells, biochemical and mutational analysis, we show that CD8 binding to pMHC in cis involves a different docking mode and is regulated by posttranslational modifications including a membrane-distal interchain disulfide bond and negatively charged O-linked glycans near positively charged sequences on the CD8β stalk. These modifications distort the stalk, thus favoring CD8 binding to pMHC in cis. Differential binding of CD8 to pMHC in cis or trans is a means to regulate CD8+ T-cell responses and provides new translational opportunities.

• Klíčová slova
• CD8, MHC, Structure, T cell, T-cell receptor,
• MeSH
• aktivace lymfocytů imunologie   MeSH
• antigeny CD8 chemie   genetika   metabolismus   MeSH
• biologické modely MeSH
• CD8-pozitivní T-lymfocyty imunologie   metabolismus   MeSH
• histokompatibilní antigeny chemie   genetika   imunologie   MeSH
• interakční proteinové domény a motivy MeSH
• konformace proteinů MeSH
• molekulární modely MeSH
• multiproteinové komplexy chemie   imunologie   metabolismus   MeSH
• mutace MeSH
• myši knockoutované MeSH
• myši MeSH
• peptidy chemie   imunologie   metabolismus   MeSH
• sekvence aminokyselin MeSH
• vazba proteinů MeSH
• vztahy mezi strukturou a aktivitou MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• antigeny CD8 MeSH
• histokompatibilní antigeny MeSH
• multiproteinové komplexy MeSH
• peptidy MeSH