Identification of cell surface receptors for the Act-2 cytokine.
We have identified cell surface receptors for Act-2, a secreted protein expressed upon activation of T cells, B cells, and monocytes. Although 125I-Act-2 showed little, if any, specific binding to resting peripheral blood lymphocytes (PBL) receptors were readily detected on PHA/PMA-activated PBL and a variety of cell lines including MT-2, HL60, DMSO differentiated HL60, HeLa, and K562 cells. The equilibrium dissociation constant (Kd) is 3-12 nM for MT-2, K562, and PBL activated with PHA/PMA for 40-80 h. We have also identified a rabbit polyclonal antiserum that can block Act-2 binding to its receptors. The ability to detect specific Act-2 receptors and the development of a blocking antiserum should prove valuable in efforts to molecularly clone the Act-2 receptor and to dissect the biological actions of Act-2.
Napolitano
M
M
Cell Biology and Metabolism Branch, National Institute of Child Health and Human Development, Bethesda, Maryland 20892.
Seamon
K B
KB
Leonard
W J
WJ
D000595:Amino Acid Sequence; D000818:Animals; D001667:Binding, Competitive / Q000276:immunology; D001685:Biological Factors / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D054407:Chemokine CCL4; D019742:Chemokines, CC; D002851:Chromatography, High Pressure Liquid; D016207:Cytokines; D006801:Humans; D007700:Kinetics; D008214:Lymphocytes / Q000276:immunology / Q000378:metabolism; D019402:Macrophage Inflammatory Proteins; D008969:Molecular Sequence Data; D011506:Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D011817:Rabbits; D018121:Receptors, Cytokine; D011971:Receptors, Immunologic / Q000032:analysis*
C064708:Act-2 cytokine receptor; D001685:Biological Factors; C066507:CCL4 protein, human; D054407:Chemokine CCL4; D019742:Chemokines, CC; D016207:Cytokines; D019402:Macrophage Inflammatory Proteins; D011506:Proteins; D018121:Receptors, Cytokine; D011971:Receptors, Immunologic