Construction of chimeric cDNAs and expression in WEHI-231. (A) Diagram of chimeric cDNAs. Extracellular and transmembrane (TM) domains encoding cDNA fragments derived from the hPDGFRs were ligated to cDNA fragments encoding the cytoplasmic domains of murine Igα/β. (B) Surface expression of chimeric proteins and IgM on transfectants. To further characterize, the above cDNAs were also expressed in the B-cell lymphoma A20. Proteins corresponding to the predicted size of the chimeric molecules were immunoprecipitated by monoclonal antibodies to the PDGFR (Genzyme) and immunoblotted with specific antibodies against Igα or Igβ.31