T cell antigen receptor signal transduction pathways.

The T cell antigen receptor regulates the activation and growth of T lymphocytes. The initial membrane proximal event triggered by the TCR is activation of protein tyrosine kinases with the resultant phosphorylation of cellular proteins. This biochemical response couples the TCR to a divergent array of signal transduction molecules, including enzymes that regulate lipid metabolism, GTP binding proteins, serine/threonine kinases and adapter molecules. The control of cytokine gene expression is one of the mechanisms that allows the TCR to control immune responses, and this chapter discusses the role of the different TCR signal transduction pathways in linking the TCR to nuclear targets-the transcription factors that control the expression of cytokine genes.