The T-lymphocyte co-receptors of MHC glycoproteins CD4 and CD8 are known to be associated with the protein tyrosine kinase Lck via cysteine-containing sequences in the cytoplasmic domains of CD4 and CD8 and in the N-terminal domain of Lck. Here we demonstrate that a fraction of CD4 and CD8 molecules are associated with very large, detergent-resistant complexes containing several glycosylphosphatidylinositol-anchored proteins, (glyco)lipids, and protein tyrosine kinases Lck and Fyn but apparently no other major transmembrane proteins. Association of Lck and Fyn with these large complexes is, in contrast to simple CD4/CD8-Lck complexes, not sensitive to alkylation with iodoacetamide. These large complexes therefore represent an alternative way of association of CD4 and CD8 with the protein tyrosine kinases, which may play a role in signaling through these receptors.

• MeSH
• CD4 Antigens analysis   MeSH
• CD8 Antigens analysis   MeSH
• Cell Membrane chemistry   MeSH
• Glycosylphosphatidylinositols MeSH
• Humans MeSH
• Lymphocytes chemistry   MeSH
• Neoplasm Proteins * MeSH
• Lymphocyte Specific Protein Tyrosine Kinase p56(lck) MeSH
• Protein-Tyrosine Kinases analysis   classification   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• CD4 Antigens MeSH
• CD8 Antigens MeSH
• FRK protein, human MeSH Browser
• Glycosylphosphatidylinositols MeSH
• Neoplasm Proteins * MeSH
• Lymphocyte Specific Protein Tyrosine Kinase p56(lck) MeSH
• Protein-Tyrosine Kinases MeSH