Eukaryotic signal sequence transports insulin antigen in Escherichia coli.

Abstract

A series of plasmids with unique Pst restriction sites within or near the DNA that encodes the penicillinase signal sequence was made. Inserted DNA can be read in all 3 frames both within and immediately after the signal sequence. Pst-terminated DNA copies of the structural information for rat proinsulin and preproinsulin into these plasmids were cloned, forming a large number of hybrid penicillinase (bacterial) and insulin (eukaryotic) signal sequences. The levels of insulin antigen in the E. coli periplasm were compared with those inside the cells. Either the bacterial or the eukaryotic signal is sufficient to transport rat insulin antigen into the periplasmic space.