A signal sequence is not sufficient to lead β-galactosidase out of the cytoplasm

Abstract
Escherichia coli strains were constructed in which lacZ, the gene for the cytoplasmic enzyme .beta.-galactosidase, is fused to lamB, the gene for an outer membrane protein. One such strain produces a .beta.-galactosidase which remains cytoplasmic even though it possesses the complete signal sequence of the lamB protein precursor at the amino-terminal end.