GPI-Anchored Cell-Surface Molecules Complexed to Protein Tyrosine Kinases

TLDR

Ligand or antibody binding to GPI‑anchored cell‑surface proteins can activate leukocytes, yet the mechanism by which these proteins, lacking intracellular domains, transduce signals remains unknown. The study shows that GPI‑linked proteins CD59, CD55, CD48, CD24, CD14, Thy‑1, and Ly‑6 associate with protein‑tyrosine kinases, with p56 lck identified as the kinase linked to CD59, CD55, CD48 in human T cells and Thy‑1 in mouse T cells, suggesting a signal‑transduction mechanism.

Abstract

Binding of ligand or antibody to certain cell-surface proteins that are anchored to the membrane by glycophosphatidylinositol (GPI) can cause activation of leukocytes. However, it is not known how these molecules, which lack intracellular domains, can transduce signals. The GPI-linked human molecules CD59, CD55, CD48, CD24, and CD14 as well as the mouse molecules Thy-1 and Ly-6 were found to associate with protein tyrosine kinases, key regulators of cell activation and signal transduction. A protein tyrosine kinase associated with the GPI-linked proteins CD59, CD55, and CD48 in human T cells, and with Thy-1 in mouse T cells was identified as p56 lck , a protein tyrosine kinase related to Src. This interaction of GPI-linked molecules with protein tyrosine kinases suggests a potential mechanism of signal transduction in cells.