Fig. 3. The delayed cleavage of the US11 signal peptide is determined by its signal sequence and transmembrane/cytoplasmic tail region. (A) The US11 chimeric molecules US11–K^b_18–215, US11/A2_TM/CT and wild-type US11-215. (B) Processing of these molecules was examined in stable transfectants of MG-U373 cells using pulse–chase analysis. US11 was recovered from SDS lysates using α-US11 serum and analyzed by SDS–PAGE (12.5%). The signal peptide-containing form of US11 (spUS11-215) and the mature processed form of US11 (mUS11-215) are indicated. (C) The US11-215 molecules recovered from (B) were quantitated by a Molecular Dynamics Storm PhosphorImager. The US11 recovered at each time point is represented as percentage recovery of US11. The US11 recovered at the 8 min chase point was used as the 100% recovery value.