Association between the amino- and carboxyl-terminal halves of lactose permease is specific and mediated by multiple transmembrane domains. 1996

M Sahin-Tóth, and H R Kaback, and M Friedlander
Robert Mealey Laboratory for the Study of Macular Degenerations, Department of Cell Biology, Scripps Research Institute, La Jolla, California 92037, USA.

Lactose permease of Escherichia coli is a polytopic membrane transport protein containing 12 membrane-spanning segments. When the amino (N6)- and carboxy (C6)-terminal halves are expressed as separate gene fragments, association of the first half (N6) of the permease with the second half (C6) is necessary for stable insertion of C6 [Bibi, E., & Kaback, H. R. (1990) Proc. Natl. Acad. Sci. U.S.A. 87, 4325-4329]. In this report we demonstrate that N6-C6 interaction is specific, since N6 fragments derived from the structurally related tetracycline or sucrose transporters are unable to stabilize insertion of C6 from lactose permease. Furthermore, this association appears to be mediated by multiple transmembrane domains, since co-expression of progressively truncated N-terminal fragments (N5, N4, N3, N2, N1) with C6 leads to markedly decreased, but detectable amounts of C6 in the membrane. The results indicate that the N- and C-terminal six transmembrane domains of lactose permease are integrated into the membrane as separate units, and insertion of the C-terminal half is directed by specific interactions with the N-terminal half of the protein.

UI MeSH Term Description Entries
D007785 Lactose A disaccharide of GLUCOSE and GALACTOSE in human and cow milk. It is used in pharmacy for tablets, in medicine as a nutrient, and in industry. Anhydrous Lactose,Lactose, Anhydrous
D008969 Molecular Sequence Data Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories. Sequence Data, Molecular,Molecular Sequencing Data,Data, Molecular Sequence,Data, Molecular Sequencing,Sequencing Data, Molecular
D009004 Monosaccharide Transport Proteins A large group of membrane transport proteins that shuttle MONOSACCHARIDES across CELL MEMBRANES. Hexose Transport Proteins,Band 4.5 Preactin,Erythrocyte Band 4.5 Protein,Glucose Transport-Inducing Protein,Hexose Transporter,4.5 Preactin, Band,Glucose Transport Inducing Protein,Preactin, Band 4.5,Proteins, Monosaccharide Transport,Transport Proteins, Hexose,Transport Proteins, Monosaccharide,Transport-Inducing Protein, Glucose
D002462 Cell Membrane The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells. Plasma Membrane,Cytoplasmic Membrane,Cell Membranes,Cytoplasmic Membranes,Membrane, Cell,Membrane, Cytoplasmic,Membrane, Plasma,Membranes, Cell,Membranes, Cytoplasmic,Membranes, Plasma,Plasma Membranes
D003062 Codon A set of three nucleotides in a protein coding sequence that specifies individual amino acids or a termination signal (CODON, TERMINATOR). Most codons are universal, but some organisms do not produce the transfer RNAs (RNA, TRANSFER) complementary to all codons. These codons are referred to as unassigned codons (CODONS, NONSENSE). Codon, Sense,Sense Codon,Codons,Codons, Sense,Sense Codons
D004269 DNA, Bacterial Deoxyribonucleic acid that makes up the genetic material of bacteria. Bacterial DNA
D004926 Escherichia coli A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc. Alkalescens-Dispar Group,Bacillus coli,Bacterium coli,Bacterium coli commune,Diffusely Adherent Escherichia coli,E coli,EAggEC,Enteroaggregative Escherichia coli,Enterococcus coli,Diffusely Adherent E. coli,Enteroaggregative E. coli,Enteroinvasive E. coli,Enteroinvasive Escherichia coli
D005796 Genes A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms. Cistron,Gene,Genetic Materials,Cistrons,Genetic Material,Material, Genetic,Materials, Genetic
D005798 Genes, Bacterial The functional hereditary units of BACTERIA. Bacterial Gene,Bacterial Genes,Gene, Bacterial
D000595 Amino Acid Sequence The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION. Protein Structure, Primary,Amino Acid Sequences,Sequence, Amino Acid,Sequences, Amino Acid,Primary Protein Structure,Primary Protein Structures,Protein Structures, Primary,Structure, Primary Protein,Structures, Primary Protein

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