Regulation of src family tyrosine kinases in lymphocytes.

An immune response is initiated by activation of antigen-specific lymphoid cells via receptors on the cell surface. Recent advances have begun to unravel the molecular pathways by which the signals from these surface receptors are transduced into the cells and affect the cell's behavior. Phosphorylation of key regulatory proteins on specific tyrosine residues is emerging as a central mechanism to activate, modulate or translocate these regulatory proteins. In this review, we summarize the current picture on the role and regulation of the src family of protein tyrosine kinases thought to be involved in lymphocyte activation, and put forward a working hypothesis that might serve as a basis for further experimentation.