A signal sequence is not sufficient to lead beta-galactosidase out of the cytoplasm.
Escherichia coli strains have been 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.
D000595:Amino Acid Sequence; D001692:Biological Transport; D002352:Carrier Proteins / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism*; D005696:Galactosidases / Q000378:metabolism*; D005818:Genetic Engineering; D008970:Molecular Weight; D011498:Protein Precursors / Q000378:metabolism*; D013329:Structure-Activity Relationship; D001616:beta-Galactosidase / Q000378:metabolism*
D002352:Carrier Proteins; D011498:Protein Precursors; D005696:Galactosidases; D001616:beta-Galactosidase