Fig. 3. Zwittergent disrupts co-precipitation of full-length receptors and peptide fragments. Microsomes prepared from type I/type III co-transfected COS-7 cells were digested with trypsin as described in Figure 2. Microsomes were pelleted and resuspended in solubilization buffer containing 1% Triton X-100 (TX-100) or 1% Zwittergent 3-14 (Zw) and then immunoprecipitated with antibody CT1. Immunoblots were then sequentially probed with CT1, CT3, Myc and FLAG. Molecular weights of C- and N-terminal fragments are indicated by an arrow showing their weight in kilodaltons and the symbol used to designate the epitope in Figure 1. An asterisk indicates the IgG band.