A series of hybrid genes has been constructed by fusion of the gene (lamB) coding for the outer membrane λ receptor protein (LamB), and the gene coding for the cytoplasmic enzyme β-galactosidase, lacZ. The resultant hybrid proteins of this series contain varying amounts of LamB at the NH2 terminus and a constant amount of functional β-galactosidase at the COOH terminus. The amount of lamB-coded protein present varies from two to about 270 amino acids of the 450 amino acids found in the mature LamB protein. The largest hybrid protein is novel, exhibiting several unique properties. It is efficiently localized to the outer membrane, exhibits an extremely low β-galactosidase specific activity, and is insoluble in Triton X-100. Other hybrid proteins, containing shorter LamB sequences, are localized less efficiently or not at all. The results suggest that additional information within LamB, residing downstream from the NH2-terminal signal sequence, is required for proper routing of the protein to the outer membrane.
All Science Journal Classification (ASJC) codes
- Structural Biology
- Molecular Biology