Signal transduction through the CD4 receptor involves the activation of the internal membrane tyrosine-protein kinase p56lck

A Veillette, MA Bookman, EM Horak, LE Samelson… - Nature, 1989 - nature.com
A Veillette, MA Bookman, EM Horak, LE Samelson, JB Bolen
Nature, 1989nature.com
Abstract THE CD4 T-cell surface antigen is an integral membrane gly-coprotein of relative
molecular mass 55,000 which binds class II major histocompatibility complex (MHC)
molecules expressed on antigen presenting cells (APCs). It is thought to stabilize physical
interactions between T cells and APCs (for a review, see ref. 1). Evidence is accumulating
that suggests that CD4 can transduce an independent signal during T-cell activation2–4. It
has recently been shown that CD4 expressed on human5, 6 and murine6 T cells is …
Abstract
THE CD4 T-cell surface antigen is an integral membrane gly-coprotein of relative molecular mass 55,000 which binds class II major histocompatibility complex (MHC) molecules expressed on antigen presenting cells (APCs). It is thought to stabilize physical interactions between T cells and APCs (for a review, see ref. 1). Evidence is accumulating that suggests that CD4 can transduce an independent signal during T-cell activation2–4. It has recently been shown that CD4 expressed on human5,6 and murine6 T cells is physically associated with the Src-related tyrosine protein kinase p56lck (refs 7, 8). These results indicate that CD4 can function as a signal transducer and suggest that tyrosine phosphorylation events may be important in CD4-mediated signalling. Here, we present evidence that cross-linking of the CD4 receptor induces a rapid increase in the tyrosine-specific protein kinase activity of p56lck and is associated with the rapid phosphorylation of one of the subunits (ζ) of the T-cell receptor complex on tyrosine residues. These data provide direct evidence for a specific CD4 signal transduction pathway that is mediated through p56lck and suggest that some of the tyrosine phosphorylation events detected during antigen-mediated T-cell activation may result from signalling through this surface molecule.
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