Turnover of Proteins and Glycoproteins of Plasma Membranes in Liver, Regenerating Liver, and Morris Hepatomas

Reutter, Werner; Tauber, Rudolf; Vischer, Peter; Harms, Erik; Grünholz, Hans-Joachim; Bauer, Ch.

doi:10.1016/b978-0-12-636150-6.50051-9

Cited by 13 publications

(5 citation statements)

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“…These new uptake mechanisms could depend on variables such as plasma membrane microviscosity or the lateral mobility of membrane components, both of which are affected by colchicine (10,11). The effect of colchicine and vinblastine could be due to changes in composition (33) and turnover (15,34) of membrane proteins and glycoproteins in hepatomas. Finally, colchicine and vinblastine disaggregate the microtubular cytoskeleton in hepatomas.…”

Section: Methodsmentioning

confidence: 99%

A colchicine-sensitive uptake system in Morris hepatomas.

Tauber¹,

Reutter²

1980

Proc. Natl. Acad. Sci. U.S.A.

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' The interference of microtubular disruptors with the-uptake of amino acids and other low molecular weight substrates has been studied in Morris hepatomas, host liver, and regenerating liver. Colchicine inhibits amino acid transport (ct-aminoisobutyric acid, L-methionine, and L-leucine) in hepatomas by 59-98% whereas transport in host and regenerating liver is not impeded but increased. In hepatomas, treatment with colchicine also reduces the uptake of L-fcose, cytidine, urea, and carbonate. Vinblastine, but not lumicolchicine or cytochalasin B, is an effective inhibitor. The inhibition of uptake is not linked to a decrease of cellular ATP and UTP. The data suggest that the transport of low molecular weight substrates in hepatomas is related to microtubules or other colchicine-binding structures, e.g., of the plasma membrane. This colchicine-sensitive uptake system in hepatomas may be due to the malignant transformation of hepatocytes.

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Section: Methodsmentioning

confidence: 99%

A colchicine-sensitive uptake system in Morris hepatomas.

Tauber¹,

Reutter²

1980

Proc. Natl. Acad. Sci. U.S.A.

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“…Previous studies were mainly concerned with the overall turnover of total plasma membrane glycoproteins (for reviews, see refs. 6 and 7) and were not informative as to how single membrane glycoproteins are degraded. Thus far, breakdown of the carbohydrate and protein moieties of isolated glycoproteins has been compared in two recent studies with controversial results.…”

mentioning

confidence: 99%

Intramolecular heterogeneity of degradation in plasma membrane glycoproteins: evidence for a general characteristic.

Tauber¹,

Park²,

Reutter³

1983

Proc. Natl. Acad. Sci. U.S.A.

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Five integral plasma membrane glycoproteins (60, 80, 120, 140, and 160 kilodaltons) were isolated to homogeneity from rat liver by a four-step procedure: (i) extraction of plasma membranes with lithium diiodosalicylate, (ii) solubiization of glycoproteins with Nonidet P-40, (iii) affinity chromatography on concanavalin A-Sepharose, and (iv) semipreparative NaDodSO4/ polyacrylamide gel electrophoresis. The glycoproteins contained 48.5-51.5% hydrophobic amino acids. Carbohydrate moieties contained N-acetyl-D-glucosamine, D-mannose, D-galactose, L-fucose, and N-acetylneuraminic acid. N-Acetyl-D-galactosamine was not detectable. Half-lives of degradation of the carbohydrate and protein moieties of the five glycoproteins were measured by pulsechase experiments in vivo. Protein moieties had half-lives ranging from 52 to 88 hr in the five glycoproteins, with a mean of 73 + 15 hr. Terminal sugars, L-fucose, and N-acetylneuraminic acid had significantly shorter half-lives, averaging 18 ± 2 hr and 29 + 3 hr, respectively. The half-life of D-mannose varied between that of the terminal sugars and that of the protein moiety, depending on the type of the glycoprotein. The data show that the carbohydrate moieties are degraded faster than the protein portion of the glycoproteins. As this finding was obtained in each of the five glycoproteins, intramolecular heterogeneity of breakdown may be a general characteristic of plasma membrane glycoproteins in liver.Carbohydrate moieties of plasma membrane glycoproteins exert a key role in mediating cell surface functions (1, 2). Regulation of these functions is partly achieved by modification of the oligosaccharides (3), presumably during glycoprotein biosynthesis and breakdown. Whereas the biosynthetic pathway of membrane glycoproteins is fairly well understood (4, 5), little is known about the mode and the role of the breakdown of membrane glycoproteins. Previous studies were mainly concerned with the overall turnover of total plasma membrane glycoproteins (for reviews, see refs. 6 and 7) and were not informative as to how single membrane glycoproteins are degraded. Thus far, breakdown of the carbohydrate and protein moieties of isolated glycoproteins has been compared in two recent studies with controversial results. In dipeptidylpeptidase IV from the plasma membrane, terminal sugars turned over several times during the life-span of the molecule, indicating an independent loss and reattachment of terminal sugars (8,9 Isolation of Plasma Membranes. Plasma membranes were isolated by zonal centrifugation (11). Membrane purity was routinely checked by assay of marker enzymes and by electron microscopy as reported (12).Isolation of Glycoproteins from the Plasma Membrane. Plasma membranes (20 mg) were suspended in 4 ml of 25 mM LiSalI2/1 mM Tris HCI, pH 7.8, for 1 hr at 40C, followed by centrifugation (105,000 x g for 1 hr). The pellet was homogenized by 20 strokes in a loose-fitting Dounce homogenizer in 4 ml of 50 mM sodium borate, pH 8.0/150 mM NaCl/1 mM CaCl2/0.02% Na azide ...

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“…As a major component of all cell surfaces, carbohydrates are involved in many important biological processes, such as cellular communication, signal transduction, and pathogen recognition . Among these, the adhesion of bacteria to their host cells is of great interest in current research as bacterial infections constitute a major global health problem .…”

Section: Introductionmentioning

confidence: 99%

Sequence‐Defined Introduction of Hydrophobic Motifs and Effects in Lectin Binding of Precision Glycomacromolecules

Boden

Reise

Kania

et al. 2019

Macromolecular Bioscience

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This study investigates the influence of an increasingly hydrophobic backbone of multivalent glycomimetics based on sequence‐defined oligo(amidoamines) on their resulting affinity toward bacterial lectins. Glycomacromolecules are obtained by stepwise assembly of tailor‐made building blocks on solid support, using both hydrophobic aliphatic and aromatic building blocks to enable a gradual change in hydrophobicity of the backbone. Their binding behavior toward model lectin Concanavalin A (ConA) is evaluated using isothermal titration calorimetry (ITC) and surface plasmon resonance (SPR) showing higher affinities for glycomacromolecules with higher content of hydrophobic and aromatic moieties in the backbone. Finally, glycomacromolecules are tested in a bacterial adhesion inhibition study against Escherichia coli where more hydrophobic backbones yield higher inhibitory potentials most likely due to additional secondary interactions with hydrophobic regions of the protein receptor as well as a change in conformation exposing carbohydrate ligands for increased binding. Overall, the results highlight the influence and thereby importance of the polymer backbone itself on the resulting properties of polymeric biomimetics.

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Turnover of Proteins and Glycoproteins of Plasma Membranes in Liver, Regenerating Liver, and Morris Hepatomas

Cited by 13 publications

References 0 publications

A colchicine-sensitive uptake system in Morris hepatomas.

A colchicine-sensitive uptake system in Morris hepatomas.

Intramolecular heterogeneity of degradation in plasma membrane glycoproteins: evidence for a general characteristic.

Sequence‐Defined Introduction of Hydrophobic Motifs and Effects in Lectin Binding of Precision Glycomacromolecules

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