Immunoprecipitation analysis of carbimazole-dependent antibodies with PECAM-1 mutants.

Untransfected L-cells and L-cells expressing the entire PECAM-1 or lacking the first (Δ1) or the second (Δ2) extracellular immunoglobulin homology domain were surface labeled with biotin. After lysis, immunoprecipitation was performed with sera containing carbimazole-dependent antibodies in the presence of the drug (A) and with mab PECAM-1.2 against the extracellular loop 6 of PECAM-1 (B). Lane 1: untransfected L-cells, lane 2: PECAM-1 transfectant, lane 3: Δ1-PECAM-1 transfectant, and lane 4: Δ2-PECAM-1 transfectant.