ASSOCIATION OF GPI-ANCHORED GLYCOPROTEINS WITH OTHER COMPONENTS OF THE LEUKOCYTE MEMBRANE

The leucocyte surface glycosylphosphatidylinositol (GPI)-anchored memb rane proteins are localized within specific membrane microdomains whic h also contain specific (glyco)lipids and intracellular proteins inclu ding protein kinases. These ''GPI-domains'' are devoid of most abundan t transmembrane proteins, but in T-cells they appear to contain small amounts of CD4 and CD8 and in B-cell lines, small amounts of CD10. The existence of these relatively detergent-resistant membrane microdomai ns explains the signal-transducing ability of GPI-anchored receptors. In addition to the ''GPI-microdomains'', several other types of analog ous very large detergent-resistant complexes/domains appear to exist, such as those containing T-cell receptor, others containing CD45R mole cules associated with a protein kinase, and still others composed main ly of several proteins of the tetraspan family. Therefore, we suggest that the leucocyte surface is a mosaic of microdomains of unique compo sition associated with specific signal-transducing molecules.