Hybrid plasmids carrying trg, the genetic locus in closest proximity to terC, coded for several polypeptides in addition to the Trg protein. Polypeptides of 59,000 and 61,000 apparent molecular weight were the most prominent products synthesized in minicells containing the hybrid plasmids. Analysis of the effects of deletions generated by a restriction endonuclease identified a region of DNA immediately adjacent to trg as the putative gene coding for the two polypeptides. Studies with whole cells and minicells showed that the 59,000-dalton polypeptide is a periplasmic protein. Analysis by limited proteolysis indicated that the two polypeptides are related, and a number of observations support the notion that the 61,000-dalton protein is a precursor form of the 59,000-dalton mature exported protein. The identification and characterization of a protein, in addition to Trg, which is produced by a gene in close proximity to terC emphasizes the fact that the region does contain intact and active genes.