Ly-6 superfamily members Ly-6A/E, Ly-6C, and Ly-6I recognize two potential ligands expressed by B lymphocytes.
Most hemopoietic cells express one or more members of the Ly-6 supergene family of small glycosylphosphatidylinositol-linked proteins. Although levels of Ly-6 proteins vary with stages of differentiation and activation, their function largely remains unknown. To ascertain whether ligands for Ly-6 proteins exist, chimeric proteins were constructed in which Ly-6E, Ly-6C, and Ly-6I were fused to the murine IgM heavy chain. These chimeras specifically stained both developing and mature B lymphocytes, as assessed by flow cytometry. Analysis of variants of the CH27 B cell lymphoma revealed that Ly-6A/E and Ly-6I recognized different molecules. CH27 cells with low levels of Ly-6A/E ligand activity also lost expression of CD22, and cells transfected with CD22 gained the ability to bind the Ly-6A/E chimera and, to a lesser extent, the Ly-6C and Ly-6I chimeric proteins. As many mature B cells coexpress Ly-6A/E and CD22, the function of Ly-6 molecules may be to associate with other membrane proteins, possibly concentrating these ligands in lipid rafts, rather than acting directly as cell:cell adhesion molecules.
Pflugh
David L
DL
Section of Immunobiology, Yale University School of Medicine, New Haven, CT 06520, USA.
Maher
Stephen E
SE
Bothwell
Alfred L M
AL
D000818:Animals; D015703:Antigens, CD / Q000235:genetics / Q000378:metabolism*; D000944:Antigens, Differentiation, B-Lymphocyte / Q000235:genetics / Q000378:metabolism*; D000950:Antigens, Ly / Q000235:genetics / Q000378:metabolism*; D016175:B-Lymphocyte Subsets / Q000276:immunology* / Q000378:metabolism*; D018957:CD59 Antigens / Q000096:biosynthesis / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D016466:CHO Cells; D019556:COS Cells; D015815:Cell Adhesion Molecules; D006224:Cricetinae; D014644:Genetic Variation / Q000276:immunology; D007127:Immunoglobulin Constant Regions / Q000235:genetics; D007148:Immunoglobulin mu-Chains / Q000235:genetics; D037102:Lectins / Q000235:genetics / Q000378:metabolism*; D008024:Ligands; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D005810:Multigene Family / Q000276:immunology*; D022423:Myeloid Cells / Q000276:immunology / Q000378:metabolism; D011485:Protein Binding / Q000235:genetics / Q000276:immunology; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D051918:Sialic Acid Binding Ig-like Lectin 2; D014162:Transfection; D014407:Tumor Cells, Cultured
D015703:Antigens, CD; D000944:Antigens, Differentiation, B-Lymphocyte; D000950:Antigens, Ly; D018957:CD59 Antigens; C497868:Cd22 protein, mouse; D015815:Cell Adhesion Molecules; D007127:Immunoglobulin Constant Regions; D007148:Immunoglobulin mu-Chains; D037102:Lectins; D008024:Ligands; C074650:Ly6a protein, mouse; C499392:Ly6i protein, mouse; D008565:Membrane Proteins; D011993:Recombinant Fusion Proteins; D051918:Sialic Acid Binding Ig-like Lectin 2