ABSTRACT
The leucocyte surface glycosylphosphatidylinositol (GPI)-anchored membrane proteins are localized within specific membrane microdomains which also contain specific (glyco)lipids and intracellular proteins including protein kinases. These "GPI-domains" are devoid of most abundant 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 microdomains explains the signal-transducing ability of GPI-anchored receptors. In addition to the "GPI-microdomains", several other types of analogous very large detergent-resistant complexes/domains appear to exist, such as those containing T-cell receptor, others containing CD45R molecules associated with a protein kinase, and still others composed mainly of several proteins of the tetraspan family. Therefore, we suggest that the leucocyte surface is a mosaic of microdomains of unique composition associated with specific signal-transducing molecules.
Subject(s)
Antigens, CD/analysis , Antigens, Surface/analysis , Glycosylphosphatidylinositols/chemistry , Leukocytes/chemistry , Membrane Glycoproteins/analysis , Antigens, CD/chemistry , Antigens, Surface/chemistry , B-Lymphocytes/chemistry , B-Lymphocytes/immunology , Glycosylphosphatidylinositols/biosynthesis , Humans , Leukocytes/immunology , Membrane Glycoproteins/chemistry , T-Lymphocytes/chemistry , T-Lymphocytes/immunologyABSTRACT
The leucocyte surface glycosylphosphatidylinositol (GPI)-anchored membrane proteins are localized within specific membrane microdomains which also contain specific (glyco)lipids and intracellular proteins including protein kinases. These "GPI-domains" are devoid of most abundant 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 microdomains explains the signal-transducing ability of GPI-anchored receptors. In addition to the "GPI-microdomains", several other types of analogous very large detergent-resistant complexes/domains appear to exist, such as those containing T-cell receptor, others containing CD45R molecules associated with a protein kinase, and still others composed mainly of several proteins of the tetraspan family. Therefore, we suggest that the leucocyte surface is a mosaic of microdomains of unique composition associated with specific signal-transducing molecules