Characteristics of SLF binding to the c-kit associated with CD63.

(A) MO7e cells were treated with 5 times increasing concentrations of¹²⁵I-labeled SLF at 37°C for 5 minutes. After cross-linking with BS3, cells were solubilized with lysis buffer containing 1% CHAPS and processed for immunoprecipitation with anti-CD63 or anti–c-kit antibody. After being separated by SDS-PAGE, c-kit bound to radiolabeled SLF was detected by autoradiography (upper panel). The same membrane was immunoblotted with anti–c-kit polyclonal antibody (lower panel). These are the representative results from 4 separate experiments. (B) MO7e cells were treated with¹²⁵I-labeled SLF (10⁶ cpm/10⁷cells/mL) for indicated time periods at 37°C. After cross-linking and subsequent immunoprecipitation with CD63, radioactivities of immunoprecipitates were measured with a γ counter. These are the representative results from 2 separate experiments.