@article{KruseShenArnoldetal.1993, author = {Kruse, N. and Shen, B. J. and Arnold, S. and Tony, H. P. and M{\"u}ller, T. and Sebald, Walter}, title = {Two distinct functional sites of human interleukin 4 are identified by variants impaired in either receptor binding or receptor activation}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62451}, year = {1993}, abstract = {Interleukin 4 (IL-4) exerts a decisive role in the coord.ination of proteelive immune responses against parasites, particularly helminths. A disregulation of ll.r4 function is possibly involved in the genesis of allergic disease states. The search for important amino acid residues in human ll.r4 by mutational analysis of charged invariant amino acid positions identified two distinct functional sites in the 4-helix-bundle protein. Site 1 was marked by amino acid substitutions of the glutamic acid at position 9 in helix A and arginine at position 88 in helix C. Exchanges at both positions led to IL-4 variants deficient in binding to the extracellular domain of the ll.r4 receptor (IL-4ReJ. In parallel, up to 1000-fold increased concentrations of this type of variant were required to induce T -cell proliferation and B-eeil CD23 expression. Site 2 was marked by amino acid exchanges in helix D at positions 121, 124 and 125 (arginine, tyrosine and serine respectively in the wild-type).ß.A variants affected at site 2 exhibited partial agonist activity during T -cell proliferation; however, they still bound with high affinity to IL-4Rex. [The generation of an IL-4 antagonist by replacing tyrosine 124 with aspartic acid has been described before by Kruse et al. (1992) (EMBO }., 11, 3237-3244)]. These findings indicate that IL-4 functions by bind.ing IL-4Rex via site 1 which is constituted by residues on helices A and C. They further suggest that the association of a second, still undetined receptor protein with site 2 in helix D activates the receptor system and generates a transmembrane signal.}, subject = {Biochemie}, language = {en} } @article{McCarthySchairerSebald1985, author = {McCarthy, J. E. and Schairer, H. U. and Sebald, Walter}, title = {Translational initiation frequency of atp genes from Escherichia coli: identification of an intercistronic sequence that enhances translation}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62657}, year = {1985}, abstract = {The c, b and {\"o} subunit genes of the Escherichia coli atp operon were cloned individually in an expression vector between the tac fusion promoter and the galK gene. The relative rates of subunit synthesis directed by the cloned genes were similar in vitro andin vivo and compared favourably with the subunit stoichiometry of the assembled proton-translocating A TP synthase of E. coli in vivo. The rate of synthesis of subunit c was at least six times that of subunit b and 18 times that of subunit {\"o}. Progressive shortening of the long intercistronic sequence lying upstream of the subunit c gene showed that maximal expression of this gene is dependent upon the presence of a sequence stretching > 20 bp upstream of the Shine-Dalgarno site. This sequence thus acts to enhance the rate of translational initiation. The possibility that similar sequences might perform the same function in other operons of E. coli and bacteriophage A is also discussed. Translation of the subunit b cistron is partially coupled to translation of the preceding subunit c cistron. In conclusion, the expression of all the atp operon genes could be adjusted to accommodate the subunit requirements of A TP synthase assembly primarily by means of mechanisms which control the efficiency of translational initiation and re-initiation at the respective cistron start codons.}, subject = {Biochemie}, language = {en} } @article{HoppeSebald1986, author = {Hoppe, J. and Sebald, Walter}, title = {Topological studies suggest that the pathway of the protons through F\(_0\) is provided by amino acid residues accessible from the lipid phase}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62602}, year = {1986}, abstract = {The structure of the F0 part of ATP synthases from E. coli and Neurospora crassa was analyzed by hydrophobic surface labeling with [125I]TID. In the E. co/i F0 all three subunits were freely accessible to the reagent, suggesting that these subunits are independently integrated in the membrane. Labeted amino acid residues were identified by Edman degradation of the dicyclohexylcarbodiimide binding (DCCD) proteins from E. coli and Neurospora crassa. The very similar patterns obtained with the two homologaus proteins suggested the existence of tightly packed cx-helices. The oligomeric structure of the DCCD binding protein appeared to be very rigid since little, if any, change in the labeling patternwas observed upon addition of oligomycin or DCCD to membranes from Neurospora crassa. When membrancs were pretrcated with DCCD prior to the reaction with [125I]TID an additionally labeled amino acid appeared at the position of Glu·65 which binds DCCD covalently, indicating the Jocation of this inhibitor on the outside of the oligomer. It is suggested that proton conduction occurs at the surface of the oligomer of the DCCD binding protein. Possibly this oligomer rotates against the subunit a or b and thus enables proton translocation. Conserved residues in subunit a, probably located in the Iipid bilayer, might participate in the pro· ton translocation mechanism.}, subject = {Biochemie}, language = {en} } @article{SchairerHoppeSebaldetal.1982, author = {Schairer, H. U. and Hoppe, J. and Sebald, Walter and Friedl, P.}, title = {Topological and functional aspects of the proton conductor, F\(_0\), of the Escherichia coli ATP-synthase}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62721}, year = {1982}, abstract = {The isolated H\(^+\) conductor, F\(_0\) , of the Escherichia co1i ATP-synthase consists of three subunits, a, b, and c. H\(^+\) -permeable liposomes can be reconstit~ted with F\(_0\) and lipids; addition of F\(_1\)-ATPase reconstitutes a functional ATP-synthase. Mutants with altered or misslng F\(_0\) subunits are defective in H\(^+\) conduction. Thus, all three subunits are necessary for the expression of H\(^+\) conduction. The subunits a and b contain binding sites for F\(_1\)• Computer calculations, cross-links, membrane-permeating photo-reactive labels, and proteases were used to develop tentative structural models for the individual F\(_0\) subunits.}, subject = {Biochemie}, language = {en} } @article{FlueggeFischerGrossetal.1989, author = {Fl{\"u}gge, U. I. and Fischer, K. and Gross, A. and Sebald, Walter and Lottspeich, F. and Eckerskorn, C.}, title = {The triose phosphate-3-phosphoglycerate-phosphate translocator from spinach chloroplasts: nucleotide sequence of a full-length cDNA clone and import of the in vitro synthesized precursor protein into chloroplasts}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62559}, year = {1989}, abstract = {No abstract available}, subject = {Biochemie}, language = {en} } @article{HoppeFriedlSchaireretal.1983, author = {Hoppe, J. and Friedl, P. and Schairer, H. U. and Sebald, Walter and Meyenburg, K. von and Jorgensen, B. B.}, title = {The topology of the proton translocating F\(_0\) component of the ATP synthase from E. coli K12: studies with proteases}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62718}, year = {1983}, abstract = {The accessibility of the three F\(_0\) subunits a, b and c from the Escherichia coli Kll A TP synthase to various proteases was studied in F\(_1\)-depleted inverted membrane vesicles. Subunit b was very sensitive to all applied proteases. Chymotrypsin produced a defined fragment of mol. wt. 1S 000 which remained tightly bound to the membrane. The cleavage site was located at the C-terminal region of subunit b. Larger amounts of proteases were necessary to attack subunit a (mol. wt. 30 000). There was no detectable deavage of subunit c. It is suggested that the major hydrophilic part of subunit b extends from the membrane into the cytoplasm and is in contact with the F\(_1\) sector. The F\(_1\) sector was found to afford some protection against proteolysis oftheb subunit in vitro andin vivo. Protease digestion bad no influence on the electro-impelled H\(^+\) conduction via F\(_0\) bot ATP-dependent H\(^+\) translocation could not be reconstituted upon binding of F\(_1\)• A possible role for subunit b as a linker between catalytic events on the F\(_1\) component and the proton pathway across the membrane is discussed.}, subject = {Biochemie}, language = {en} } @article{HoppeSchairerSebald1980, author = {Hoppe, J. and Schairer, H. U. and Sebald, Walter}, title = {The proteolipid of a mutant ATPase from Escherichia coli defective in H\(^+\)-conduction contains a glycine instead of the carbodiimide-reactive aspartyl residue}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62769}, year = {1980}, abstract = {No abstract available}, subject = {Biochemie}, language = {en} } @article{HarnischWeissSebald1985, author = {Harnisch, U. and Weiss, H. and Sebald, Walter}, title = {The primary structure of the iron-sulfur subunit of ubiquinol-cytochrome c reductase from Neurospora, determined by cDNA and gene sequencing}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62631}, year = {1985}, abstract = {No abstract available}, subject = {Biochemie}, language = {en} } @article{RoemischTropschugSebaldetal.1987, author = {R{\"o}misch, J. and Tropschug, M. and Sebald, Walter and Weiss, H.}, title = {The primary structure of cytochrome c\(_1\) from Neurospora crassa}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62578}, year = {1987}, abstract = {No abstract available}, subject = {Biochemie}, language = {en} } @article{GesslerGrupeGrzeschiketal.1992, author = {Gessler, Manfred and Grupe, Andrew and Grzeschik, Karl-Heinz and Pongs, Olaf}, title = {The potassium channel gene HK1 maps to human chromosome 11p14.1, close to the FSHB gene}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-59184}, year = {1992}, abstract = {Transiently activating (A-type) potassium (K) channels are important regulators of action potential and action potential firing frequencies. HK1 designates the firsthuman cDNA that is highly homologous to the rat RCK4 cDNA that codes for an A-type K-channel. The HK1 channel is expressed in heart. By somatic cell hybrid analysis, the HK1 gene has been assigned to human chromosome 11p13-pl4, the WAGR deletion region (Wilms tumor, aniridia, genito-urinary abnormalities and mental retardation). Subsequent pulsed field gel (PFG) analysis and comparison with the well-established PFG map of this region localized the gene to 11p14, 200-600 kb telomeric to the FSHB gene.}, subject = {Biochemie}, language = {en} }