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R Prinz

Publications and source records attributed to R Prinz.

10 recordsLinked to original sources
PubMed1979

Effect of lectins on the metabolism of sulfated glycosaminolycans in cultured fibroblasts.

A short exposure of human skin fibroblasts to Concanavalin A and wheat germ agglutinin led to an intra- and extracellular accumulation of sulfated glycosaminoglycans. The intracellular accumulation was caused by an impaired degradation of sulfated glycosaminoglycans. The increase of extracellular and cell surface associated 35S-labeled proteoglycans could be ascribed to a lectin-mediated inhibition of endocytosis of these polysaccharides. Results obtained with mono- and divalent Concanavalin A derivatives were in agreement with the view that lectins inhibit endocytosis of sulfated proteoglycans by binding to the cell surface receptors specific for these polysaccharides. Proteoglycans secreted by fibroblasts formed precipitable complexes with Concanavalin A. Complex formation reduced markedly the uptake of the proteoglycan. All effects on glycosaminoglycan metabolism mediated by Concanavalin A and wheat germ agglutinin could be prevented by methyl alpha-D-mannoside and N-acetylglucoseamine, respectively.

Cells, Cultured↗
PubMed1978

Endocytosis of sulphated proteoglycans by cultured skin fibroblasts.

1. Human skin fibroblasts internalize homologous sulphated proteoglycans by adsorptive endocytosis. Endocytosis rate is half maximal when the concentration of the proteoglycans is 0.1 nM. At saturation, a single fibroblast may endocytose up to 8 X 10(6) proteoglycan molecules/h. 2. The kinetics of prote;glycan binding to the cell surface suggest the presence of 6 X 10(5) high-affinity binding sites per cell. The bulk of sulphated proteoglycans associates to low-affinity binding sites on the cell surface. 3. Glycosaminoglycans and other anionic macromolecules inhibit endocytosis of sulphated proteoglycans non-competitively. The lack of interaction of glycosaminoglycans with the cell-surface receptors for sulphated proteoglycans suggests that the protein core of proteoglycans is essential for binding to the cell surface. 4. The effects of trypsin, cell density, serum concentration and medium pH on endocytosis and degradation of endocytosed sulphated proteoglycans is described. 5. A comparison of the number of the high-affinity binding sites and the number of molecules endocytosed with respect to time suggests a recycling of the proteoglycan receptors between the cell surface and the endocytotic vesicles and/or the lysosomes.

Cell Count↗
PubMed1975

Cuprodoxin.

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Amino Acids↗
PubMed1975

A naturally occurring Cu-thionein in Saccharomyces cerevisiae.

A naturally occurring monodisperse Cu-thionein was prepared using ammonium sulfate precipitation followed by ion exchange (DEAE 23) and gel chromatography (Sephadex G-75). The chromatographic steps were repeated at least twice, or until the Cu-thionein remained homogeneous when subjected to analytical polyacrylamide disc electrophoresis. The molecular weight of this copper protein was 9500+/-500. Up to 24.3% cysteine residues were determined, indicating the relationship to the metallothioneins. Aromatic amino acids were virtually absent, while there were about three times as many acidic amino acid residues, including aspartate and glutamate, as in metallothioneins. 10 g atoms of Cu were measured per mole of protein. The copper binding strength of thionein was extremely high. Displacement by protons (pH 1.5) and gel chromatography or dialysis employing EDTA were not effective. Dialysis against diethyldithiocarbamate produced a protein essentially free of copper. Both the ultraviolet properties and the circular dichroism measurements proved identical with those properties reported for artificially prepared Cu-thionein (see ref.[1]. The major absorption was in the far ultraviolet region with a weak shoulder at 270 nm attributable to copper charge-transfer transititions. 6 Cotton extrema were seen at 213, 283 and 302 nm (negative) and 245, 328 and 359 nm (positive). The possible role of Cu-thionein as an electron transport system was discussed.

Amino Acids↗
PubMedDate not supplied

Estrogen receptor in normal and neoplastic human thyroid tissue.

Clinical evidence suggests the possible influence of estrogen on the biologic behavior of thyroid neoplasm. In this study we evaluated the distribution and characteristics of intracellular receptors for estrogen in normal and neoplastic thyroid tissue obtained from 54 patients. Forty-two percent of all specimens assayed by the protamine sulfate precipitation technique had a detectable intracellular binding site for estrogen. Differentiated carcinomas (eight of eight) and adenomas (seven of nine) had high incidences of receptors compared with goiter (five of 23) and normal thyroid (three of eight). However, there were no detectable receptors for estrogen in medullary carcinomas of the thyroid (0 of six). Also, carcinomas and adenomas had higher receptor contents than did goiter and normal differentiated thyroid tissue. There was no significant difference in the affinity of estrogen for receptors among the different histologic groups. There were both 4S and 8S receptor types, which were specific for estrogen. The binding of estrogen to thyroid tissue and differentiated neoplasm originating from thyroid tissue were comparable to the binding of estrogen to other hormone-dependent normal and neoplastic tissues.

Adenoma↗