The cysteine residues in the cytoplasmic tail of CD8 alpha are required for its coreceptor function

Mol Immunol. 1993 Jun;30(8):755-64. doi: 10.1016/0161-5890(93)90147-4.


The cytoplasmic segment of the CD8 alpha polypeptide includes both a cysteine-containing motif that is required for its association with the tyrosine kinase p56lck, and two serine residues which are likely to be phosphorylated and involved in inside-out signaling phenomena. To determine the relative importance of these residues for CD8 function, a mouse T cell hybridoma expressing a T cell receptor specific for the class I major histocompatibility product H-2Kb was transfected with a set of CD8 alpha chain genes encoding polypeptides in which the cytoplasmic cysteine or serine residues were substituted with alanine. When challenged with Kb-transfected L cells, T cell transfectants expressing CD8 alpha beta or CD8 alpha alpha dimers with substituted cytoplasmic serine residues responded nearly as well as wild-type CD8 transfectants. In marked contrast, the CD8 alpha polypeptides bearing substitutions of both cytoplasmic cysteine residues were totally impaired in their ability to complement the co-expressed T cell receptor.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • CD4-Positive T-Lymphocytes / immunology*
  • CD4-Positive T-Lymphocytes / ultrastructure
  • CD8 Antigens / chemistry*
  • Cysteine / chemistry*
  • Cytoplasm / ultrastructure
  • Gene Expression
  • Interleukin-2 / biosynthesis
  • Mice
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Oligodeoxyribonucleotides / chemistry
  • RNA, Messenger / genetics
  • Receptors, Immunologic / chemistry*
  • Signal Transduction
  • Structure-Activity Relationship


  • CD8 Antigens
  • Interleukin-2
  • Oligodeoxyribonucleotides
  • RNA, Messenger
  • Receptors, Immunologic
  • Cysteine