(A) Amino acid sequence at the N termini of ppl, MIA2, and the fusion proteins plMIA28 and plMIA23, in which the signal sequence of ppl was replaced by the first 28 or 23 amino acids of MIA2, respectively. The amino acid sequences are given in single letter code and positively (+) and negatively (−) charged amino acid side chains as well as the cleavage site for signal peptidase (gap) are indicated. The domain representing the IAP signal peptide is boxed. (B) ER transport of ppl, plMIA28, and plMIA23. Proteins were synthesized and protease treated as described in the legend to Fig. 6 (ppl: lanes 1 to 3; plMIA23:lanes 4 to 6; plMIA28: lane 7 to 9).