Identification of a cell surface 105 kd protein (Aic-2 antigen) which binds interleukin-3.
A mouse interleukin-3 (IL-3)-binding molecule that is an essential constituent of the mouse IL-3 receptor complex was identified as a cell surface protein of Mr 105 kd. A rat monoclonal antibody, anti-Aic-2 IgM, recognized and immunoprecipitated a cell surface 105 kd protein (Aic-2 antigen). The antigen (Aic-2) and IL-3 receptor were co-down-regulated upon incubation of IL-3-dependent mouse IC2 cells with either anti-Aic-2 IgM or IL-3 at 37 degrees C, whereas anti-Aic-2 did not inhibit the binding of IL-3 to IC2 cells at 15 degrees C. The Aic-2 antigen and IL-3 receptor were co-distributed on various cell lines and cell types. IL-3 was shown to bind specifically to the Aic-2 antigen (Mr 105 kd) in the immunoprecipitated complex with anti-Aic-2. Chemically cross-linking of IL-3 to surface molecules of IC2 cells produced three types of complexes with Mr 95, 140, and 200-340 kd in SDS-PAGE, and pre-incubation with anti-Aic-2 IgM at 37 degrees C reduced the intensity of the three bands to the same degree. Moreover, anti-Aic-2 immunoprecipitated these three IL-3-cross-linked complexes, whereas the same monoclonal antibody recognized a single 105 kd molecule. Anti-Aic-2 IgM enhanced IL-3-dependent growth of IC2 cells though it did not promote proliferation of IC2 cells.
Yonehara
S
S
Department of Cell Biology, Tokyo Metropolitan Institute of Medical Science, Japan.
Ishii
A
A
Yonehara
M
M
Koyasu
S
S
Miyajima
A
A
Schreurs
J
J
Arai
K
K
Yahara
I
I
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D002460:Cell Line; D005260:Female; D007075:Immunoglobulin M / Q000276:immunology; D007377:Interleukin-3 / Q000378:metabolism*; D008565:Membrane Proteins / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism*; D051379:Mice; D051381:Rats; D011917:Rats, Inbred Lew / Q000276:immunology; D016185:Receptors, Interleukin-3 / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism
D000911:Antibodies, Monoclonal; D007075:Immunoglobulin M; D007377:Interleukin-3; D008565:Membrane Proteins; D016185:Receptors, Interleukin-3; D011994:Recombinant Proteins