Internally transposed signal sequence of carp preproinsulin retains its functions with the signal recognition particle.

It is shown that the signal sequence of carp preproinsulin is functional with the dog pancreatic signal recognition particle (SRP) both when present at its normal location at the amino-terminus of the protein or when engineered to an internal location. Inhibition of translation by SRP in the absence of microsomal membranes, reconstitution by SRP of the translocation competence of high-salt inactivated microsomes and signal peptide cleavage all occur with the signal sequence being preceded by a highly charged peptide segment of 39 amino acid residues (the distance from the amino-terminus to the cleavage site of the signal peptidase is increased to 56 residues).