PubMed Health⌕ Search

Biomedical subjects

W Lesslauer

Publications and source records attributed to W Lesslauer.

72 records · Page 4Linked to original sources
PubMed1986

Biochemical characterization of the 9.3 antigens of human T-cells: simultaneous expression of disulfide-bonded 90-kilodalton dimers and free subunits at the cell surface.

Human T-lymphocytes express a heterogeneous family of 90/45-kilodalton (kDa) glycoproteins which bind the 9.3 monoclonal antibody. It was found in previous functional tests carried out with cultures of mononuclear cells or antigen-specific T-cell clones that these glycoproteins have a specific receptor function in early T-cell activation [Gmünder and Lesslauer, Eur. J. Biochem. (1984); Ottenhoff et al., (1985)]; their membrane-biochemical properties are therefore investigated. By screening a number of lines, one continuously growing human T-cell line, HPB-ALL, was identified which expresses the 9.3 antigens in a manner comparable to normal T-cells. Monomeric 45-kDa and dimeric disulfide-bonded 90-kDa forms are precipitated from alkylated surface-iodinated and [35S]methionine-cysteine-labelled cells. The labelled tryptic fragments of surface-iodinated 9.3 antigens have isoelectric points of 4.8 (17-kDa), 4.8 (3-kDa) and 6.0 (17-kDa). By limited proteolysis the 45-kDa monomers are free subunits. The subunits of the 90-kDa dimer appear to be identical. The dimer and the free subunits coexist at the native cell surface and may be in dynamic chemical equilibrium. Human T-cells thus express--in addition to the T-cell antigen receptor--a further disulfide-bonded 90-kDa (homo-) dimeric receptor molecule.

Antigens↗
PubMed1986

Identification of a new lymphocyte subset surface antigen, the expression of which disappears after in vitro and in vivo stimulation. Distribution, biochemistry, and functional studies.

Two monoclonal antibodies (MoAbs) are described (MD 2.6, IgG1 and MD 4.3, IgG2a) that react with a nonlineage specific lymphocyte subset surface antigen. This antigen is expressed on B cells, a subset of both T8+ and T4+ cells, cells that exert killer and natural killer cell activity in vitro, B cells in lymph nodes, and a small percentage of thymocytes. Expression of the antigen was found to be variable on T cells but not on B cells among individuals. Following polyclonal activation, expression of the determinant detected was lost from the cell surface. Both MD+ and MD+ cells responded to PHA and in MLC. MLC resulted in the generation of cytotoxic T lymphocytes and primed T lymphocytes in both the MD+ and MD+ subpopulations. In contrast, the response to soluble antigens was found to reside almost exclusively in the MD-subset. Immunoprecipitation indicates that the MoAbs react with an antigen that has a molecular weight of 220-240 KD which can be cleaved into subunits of 70-80 kD by beta-mercaptoethanol.

Antibodies, Monoclonal↗
PubMed1984

A 45-kDa human T-cell membrane glycoprotein functions in the regulation of cell proliferative responses.

A 45-kDa human T cell surface glycoprotein which is tightly bound in the membrane of the resting T cell is released into the cell medium in soluble form after cell growth activation by phytohemagglutinin or neuraminidase/galactose oxidase treatments. In limited proteolysis by Staphylococcus aureus V8 protease, two major 35-kDa and 27-kDa peptide fragments of the surface-iodinated 45-kDa protein are common to the membrane-bound and the released forms, but a third 18-kDa fragment is observed exclusively with the released protein. The apparent molecular masses of the deglycosylated peptide backbones of the membrane-bound and the released molecule are 30 +/- 1 kDa, although a small size difference cannot be excluded. A polyclonal rabbit anti-(T cell membrane protein) antiserum precipitates the 45-kDa protein. A monoclonal anti-(45-kDa protein) antibody precipitates the membrane-bound 45-kDa protein solubilized with octyl glucoside, but does not precipitate the released protein. In cell culture assays, the monoclonal anti-(45-kDa protein) antibody specifically enhances the cell proliferative responses in phytohemagglutinin-treated and mixed lymphocyte cultures. These observations suggest that the 45-kDa protein has a specific receptor function in the regulation of cell proliferative responses.

Antibodies, Monoclonal↗
PubMed1982

Two detergent-insoluble proteins of the human lymphocyte membrane are enriched in an isolated membrane fraction.

Human lymphocytes isolated from peripheral blood on Ficoll/Paque density gradients were surface-labelled by 125I/lactoperoxidase or 3H/reductive alkylation and lysed in buffer solutions containing non-ionic or amphoteric detergents (octylphenylpolyoxyethylenes, octylglucoside, cholylamidopropyldimethylammoniopropane sulfonate) under a variety of conditions. The cell lysate was fractionated by sedimentation or by density gradient centrifugation. The large majority of the labelled proteins is solubilized by the detergents. Two proteins of 45 000 and 30 000 molecular weight are the main detergent-insoluble, surface-labelled components. They can be fractionated from detergent lysates of cells in relatively pure form from the other membrane proteins and from nuclear material on density gradients. The same two proteins are specifically enriched in a membrane fraction isolated from a detergent-free cell homogenate by density gradient centrifugation. Cytoskeletal and other intracellular proteins remain associated with these two proteins when fractionated by either of these two independent methods.

Cell Membrane↗
PubMed1982

Human lymphocyte membrane proteins treated with neuraminidase.

Human peripheral blood lymphocytes were surface-iodinated, treated with neuraminidase from Vibrio cholerae and lysed with non-ionic detergent. In addition, surface membrane fractions were isolated from surface-iodinated cells in the absence of detergents and treated with neuraminidase after membrane isolation. The effect of neuraminidase treatment on the membrane proteins was studied by two-dimensional gel electrophoresis. One surface-labelled protein of 45 000 molecular weight which is characterized by its association with the detergent-resistant matrix of the cells and by its specific enrichment in an isolated membrane fraction, was found to be particularly sensitive to neuraminidase treatment both of intact cells and isolated membranes. A prominent labelled protein of apparent molecular weight of 60 000 is observed in the soluble fraction after neuraminidase treatment of intact cells. The analogous protein is detected when isolated membrane fractions are treated with neuraminidase.

Cell Membrane↗
PubMed1980

(10.5 A)-1 diffraction and transmembrane proteins of erythrocyte ghost membranes.

Four types of erythrocyte ghost membrane (human ghosts, human ghosts stripped of major non-integral membrane proteins, sheep ghosts and agglutinated sheep ghosts) were studied by X-ray diffraction. Specimens of oriented and stacked membranes in an aqueous environment were used for diffraction experiments. Interferences from the membrane profile and from structures within the plane of the membrane were separated in the recorded patterns. Strongly equatorial diffraction bands at (10.5 A)-1 were identified as in-plane diffraction and correlated with probable alpha-helical conformation of the transmembrane polypeptide chains of glycophorin and band III protein.

Animals↗
PubMed1978

Phytohemagglutinin and transmembrane proteins in agglutinated sheep erythrocyte ghost membranes.

Oriented and periodically stacked sheep erythrocyte ghost membrane specimens were prepared by agglutination of the ghosts with phytohemagglutinin M and sedimentation, and were studied by X-ray diffraction. The spatial orientation of the planes of the membranes in the diffracting stack was determined from the lamellar reflections of the periodic stacking. Equatorial diffraction at (10.5 A)-1 and a (1.5 A)-1 reflection were recorded which correlate with side-to-side packed transmenbrane alpha-helices in the agglutinated membrane. A broad (4.6 A)-1 ring with strong equatorial accentuation and broad maxima at about (2.2 A)-1 and (1.2 A)-1 were observed which are attributed to the hydrocarbon chain arrangement in lipid phases of the agglutinated ghost membrane.

Animals↗
PubMed1976

On the structure of agglutinated sheep red blood cell membranes.

Specimens of isolated sheep red blood cell membranes are prepared by an agglutination technique in which membranes are stacked in regular arrays. X-ray diffraction patterns are recorded from such specimens which show meridional and equatorial diffraction phenomena. The meridional reflections correspond to single lamellar repeat periods of 160-186 A. It is concluded that two asymmetric membranes are contained in the elementary period. Lipid phases with preferentially oriented hydrocarbon chains are part of the membrane structure. The stacking of the membranes is also demonstrated in the electron microscope. The X-ray scattering curve of intracellular hemoglobin of intact sheep red blood cells is recorded to a spacing of about 8 A-1. The broad diffraction rings of this scattering curve are replaced by a series of rather sharp rings, when the red blood cells are agglutinated and placed in a hypertonic medium. Both the presence of a functioning membrane and the agglutination appear to be essential for the full expression of this phenomenon.

Animals↗
PubMed1972

Direct determination of the structure of barium stearate multilayers by x-ray diffraction.

Diffraction of X-rays is recorded from barium stearate multilayer systems with from 2 to 60 double layers or unit cells. The generalized Patterson function P'(x) is calculated by an integral Fourier transform of observed intensity data from a specimen containing only two unit cells. The Patterson function P(0)(x) of a single unit cell is determined from P'(x) and the electron density distribution of a bimolecular leaflet is obtained by a deconvolution procedure of P(0)(x) after Hosemann and Bagchi. The electron density distribution is also calculated independently by a conventional Fourier synthesis with an experimentally established set of phases. The results of the two methods are consistent and fit a physical model of the bimolecular leaflet. A direct analysis, therefore, can be performed if diffraction is observed from multilayer systems with a small number of unit cells.

Barium↗
PubMed1972

X-ray diffraction studies of lecithin bimolecular leaflets with incorporated fluorescent probes.

X-ray diffraction studies on dispersions and oriented multilayers of dipalmitoyllecithin and different fluorescent probe molecules are reported. Analysis of the diffraction data provides the electron density profile for the different bilayers to 6- to 8-Angstrom resolution. The location of the probe molecules in the bilayer structure and the perturbation of the lecithin bilayer produced by the probes are discussed.

Aniline Compounds↗