Proper insertion of a complex membrane protein in the absence of its amino-terminal export signal.
The MalF protein spans the Escherichia coli cytoplasmic membrane eight times. Deletion of the first transmembrane stretch of MalF, which acts as an export signal, results in a truncated protein that still exhibits high levels of maltose transport activity. These and additional results indicate that the orientation of a membrane protein is not determined by the amino-terminal export signal, topological information is distributed throughout the MalF protein, and insertion of a protein into the cytoplasmic membrane can occur nonsequentially.
Ehrmann
M
M
Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115.
Beckwith
J
J
D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D001693:Biological Transport, Active; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins; D058619:Maltose-Binding Proteins; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009004:Monosaccharide Transport Proteins; D016297:Mutagenesis, Site-Directed; D021382:Protein Sorting Signals / Q000378:metabolism*
D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; D058619:Maltose-Binding Proteins; D008565:Membrane Proteins; D009004:Monosaccharide Transport Proteins; D021382:Protein Sorting Signals; C461599:maltose transport system, E coli