FIG. 4.

In vitro transcription and translation of the mutant cDNAs with alteration in one of the two recognition motifs for signal peptidase. The WT M gene cDNA (WT) and the mutated M gene cDNAs (SP-2 and SP-1) were transcribed and then translated in vitro in the presence (+) or absence (−) of dog pancreas microsomal membranes, according to the procedures described in Materials and Methods. The translation products obtained were analyzed by SDS-PAGE either directly (LYS) or after immunoprecipitation with anti-GST/CM2 serum (S) or anti-M1 monoclonal antibody (M). The immunoprecipitates obtained from COS cells transfected with pME18S-CM (a plasmid containing the WT M gene) and then labeled with [³⁵S]methionine for 1 h at 48 h posttransfection were also analyzed by SDS-PAGE (TFC).