Determinants of membrane protein topology.
The topology of the integral membrane protein MalF, which is required for maltose transport in Escherichia coli, has been analyzed using fusions of alkaline phosphatase (EC 3.1.3.1). The properties of such fusion strains support a MalF structure previously proposed on theoretical grounds. Several transmembrane segments within MalF can act as signal sequences in exporting alkaline phosphatase. Other transmembrane sequences, in conjunction with cytoplasmic domains, can stably anchor alkaline phosphatase in the cytoplasm. Our results suggest that features of the amino acid sequence (possibly the positively charged amino acids) of the cytoplasmic domains of membrane proteins are important in anchoring these domains in the cytoplasm. These studies in conjunction with our earlier results show that alkaline phosphatase fusions to membrane proteins can be an important aid in analyzing membrane topology and its determinants.
Boyd
D
D
Department of Microbiology and Molecular Biology, Harvard Medical School, Boston, MA 02115.
Manoil
C
C
Beckwith
J
J
D018528:ATP-Binding Cassette Transporters; D000469:Alkaline Phosphatase; D002352:Carrier Proteins; D004252:DNA Mutational Analysis; D004926:Escherichia coli; D029968:Escherichia coli Proteins; D058619:Maltose-Binding Proteins; D008565:Membrane Proteins; D009004:Monosaccharide Transport Proteins; D011487:Protein Conformation; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D013329:Structure-Activity Relationship
D018528:ATP-Binding Cassette Transporters; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; D058619:Maltose-Binding Proteins; D008565:Membrane Proteins; D009004:Monosaccharide Transport Proteins; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; C461599:maltose transport system, E coli; D000469:Alkaline Phosphatase