Complex formation among components of human GM-CSF receptor

. (A) Association of GM-CSF receptor α subunits with β_cprotein. Cells were treated with rhGM-CSF 100 ng/mL for 10 minutes. Lysates were then immunoprecipitated with anti-β_cpolyclonal antibody. Precipitated proteins were solubilized and subjected to immunoblotting with anti-α subunit antibody (top panel). The blot was stripped and reprobed with anti-β_c(polyclonal; bottom panel). (B) Association of Jak-2 with β_c protein. Cells were treated with rhGM-CSF as above. Lysates were immunoprecipitated with anti-β_c polyclonal antibody. Precipitated proteins were then solubilized, divided, and subjected to immunoblotting with either anti–Jak-2 (top panel) or anti-β_c (polyclonal; bottom panel). (C) Expression of α subunit proteins in transduced M1 cells. Lysates from either M1/β_c/α-1 or M1/β_c/α-2 cells were subjected to immunoprecipitation with an anti-α subunit antibody (α GM-CSF receptor) or an irrelevant isotype-matched antibody (NC). Precipitated proteins were then subjected to immunoblotting with anti-α subunit antibody. The heavy band at approximately 55 kd represents IgG heavy chain.