Signal Transduction During T Cell Development

  • Dan R. Littman
  • Craig B. Davis
  • Nigel Killeen
  • Hua Xu
Part of the Advances in Experimental Medicine and Biology book series (AEMB, volume 365)


The CD4 molecule has important roles in signaling during both T cell development and peripheral helper T cell activation1,2. The ectodomain of CD4 binds to a membrane-proximal domain of MHC class II molecules on antigen presenting cells3, while its cytoplasmic tail interacts with the cytoplasmic protein tyrosine kinase (PTK) p56 lck (lck), a member of the src family of protein tyrosine kinases (reviewed in reference 4). These properties of CD4 contribute to the simultaneous interaction of the T cell antigen receptor (TCR) and CD4 with the same MHC class II molecule and to the localization of lck to the TCR complex. It has been thought that the function of CD4 (and of the class I-specific coreceptor CD8) in signal transduction is to facilitate localization of lck within the TCR complex, thus initiating a PTK signaling cascade. However, recent studies suggest that the primary function of CD4 may be to physically stabilize the interaction of the TCR with MHC, and that a direct signaling role of the CD4-associated lck molecule may not be required4,5. In this chapter, we discuss a non-catalytic role of the CD4-associated lck molecule in facilitating T cell activation and developmental signaling.


Single Positive Thymocyte Cytoplasmic Protein Tyrosine Kinase CD45 Protein Tyrosine Phosphatase Negative Regulatory Tyrosine 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© Springer Science+Business Media New York 1994

Authors and Affiliations

  • Dan R. Littman
    • 1
    • 2
    • 3
  • Craig B. Davis
    • 1
  • Nigel Killeen
    • 1
  • Hua Xu
    • 1
    • 3
  1. 1.Departments of Microbiology and ImmunologyUniversity of California at San FranciscoSan FranciscoUSA
  2. 2.Biochemistry and BiophysicsUniversity of California at San FranciscoSan FranciscoUSA
  3. 3.Howard Hughes Medical InstituteUniversity of California at San FranciscoSan FranciscoUSA

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