T cell receptor signalling results in rapid tyrosine phosphorylation of the linker protein LAT present in detergent-resistant membrane microdomains.

Stimulation of human T cell line Jurkat results in rapid tyrosine phosphorylation of a 35-38 kDa protein that is found in large and buoyant detergent-resistant membrane microdomains containing also glycosylphosphatidylinositol (GPI)-anchored proteins, glycolipids and Src-family protein tyrosine kinases ("GPI-microdomains"). The pp35-38 was found to be identical to LAT, a recently cloned key component of the T-cell receptor signalling pathway. Moreover, a modified form of protein tyrosine kinase Lck (pp60) was newly detected in the GPI-microdomains of the anti-CD3-stimulated Jurkat cells. These data support the idea that GPI-microdomains play important roles in immunoreceptor signalling.