Gonadotropin and prostaglandins binding sites in rough endoplasmic reticulum and golgi fractions of bovine corpora lutea

1978 ◽  
Vol 191 (1) ◽  
pp. 331-340 ◽  
Author(s):  
S. Mitra ◽  
Ch.V. Rao
Keyword(s):  
Endoplasmic Reticulum ◽  
Rough Endoplasmic Reticulum ◽  
Binding Sites ◽  
Corpora Lutea

The Role of Membrane Proteins and Phospholipids in the Interaction of Ribosomes with Endoplasmic Reticulum Membranes

1975 ◽  
Vol 53 (9) ◽  
pp. 1039-1045 ◽  
Author(s):  
Serge Jothy ◽  
Jean-Louis Bilodeau ◽  
Henry Simpkins
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Proteins ◽  
Rat Liver ◽  
Rough Endoplasmic Reticulum ◽  
Binding Sites ◽  
Molecular Weights ◽  
Low Concentrations ◽  
Phospholipid Headgroups ◽  
Hydrolysis Of

Hydrolysis of the membrane proteins and phospholipid headgroups of rat liver rough endoplasmic reticulum membranes showed that the ribosomal binding sites involve membrane proteins susceptible to low concentrations of trypsin, chymotrypsin, and papain. Three membrane proteins having molecular weights of 120 000, 93 000 and 36 000 are found to be altered by trypsin and chymotrypsin treatment. Also the polar headgroup of phosphatidylinositol appears to play a role in the binding process.

scholarly journals Mobility of ribosomes bound to microsomal membranes. A freeze-etch and thin-section electron microscope study of the structure and fluidity of the rough endoplasmic reticulum.

1977 ◽  
Vol 72 (3) ◽  
pp. 530-551 ◽  
Author(s):  
G K Ojakian ◽  
G Kreibich ◽  
D D Sabatini
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Proteins ◽  
Thin Section ◽  
Rough Endoplasmic Reticulum ◽  
Binding Sites ◽  
Lateral Displacement ◽  
Homogeneous Distribution ◽  
Antibody Treatment ◽  
Section Electron ◽  
Microsomal Membranes

The lateral mobility of ribosomes bound to rough endoplasmic reticulum (RER) membranes was demonstrated under experimental conditions. High-salt-washed rough microsomes were treated with pancreatic ribonuclease (RNase) to cleave the mRNA of bound polyribosomes and allow the movement of individual bound ribosomesmfreeze-etch and thin-section electron microscopy demonstrated that, when rough microsomes were treated with RNase at 4 degrees C and then maintained at this temperature until fixation, the bound ribosomes retained their homogeneous distribution on the microsomal surface. However, when RNase-treated rough microsomes were brought to 24 degrees C, a temperature above the thermotropic phase transition of the microsomal phospholipids, bound ribosomes were no longer distributed homogeneously but, instead, formed large, tightly packed aggregates on the microsomal surface. Bound polyribosomes could also be aggregated by treating rough microsomes with antibodies raised against large ribosomal subunit proteins. In these experiments, extensive cross-linking of ribosomes from adjacent microsomes also occurred, and large ribosome-free membrane areas were produced. Sedimentation analysis in sucrose density gradients demonstrated that the RNase treatment did not release bound ribosomes from the membranes; however, the aggregated ribosomes remain capable of peptide bond synthesis and were released by puromycin. It is proposed that the formation of ribosomal aggregates on the microsomal surface results from the lateral displacement of ribosomes along with their attached binding sites, nascent polypeptide chains, and other associated membrane proteins; The inhibition of ribosome mobility after maintaining rough microsomes at 4 degrees C after RNase, or antibody, treatment suggests that the ribosome binding sites are integral membrane proteins and that their mobility is controlled by the fluidity of the RER membrane. Examination of the hydrophobic interior of microsomal membranes by the freeze-fracture technique revealed the presence of homogeneously distributed 105-A intramembrane particles in control rough microsomes. However, aggregation of ribosomes by RNase, or their removal by treatment with puromycin, led to a redistribution of the particles into large aggregates on the cytoplasmic fracture face, leaving large particle-free regions.

scholarly journals Ribosome binding sites visualized on freeze-fractured membranes of the rough endoplasmic reticulum.

1980 ◽  
Vol 85 (1) ◽  
pp. 147-152 ◽  
Author(s):  
T H Giddings ◽  
L A Staehelin
Keyword(s):  
Endoplasmic Reticulum ◽  
Rough Endoplasmic Reticulum ◽  
Binding Sites ◽  
Polypeptide Chain ◽  
Freeze Fracture ◽  
Ribosome Binding ◽  
Ribosome Binding Sites ◽  
Spiral Form ◽  
Micrasterias Denticulata ◽  
Polypeptide Chains

Freeze-fracture micrographs of cells of the green alga Micrasterias denticulata stabilized by ultrarapid freezing reveal imprints of polysomes on the rough endoplasmic reticulum membranes. The imprints appear as broad, spiral ridges on the P faces and as corresponding wide grooves on the E faces of the membranes. Distinct 110-A particles with a spacing of 270 +/- 45 A are associated with the P-face ridges. Where imprints of individual ribosomes can be discerned, it is seen that there is a 1:1 relationship between the ribosomes and the 110-A particles, and that the 110-A particles are located in a peripheral position with respect to the polysome spirals. We propose that the 110-A particles could be structural equivalents of ribosome-binding sites, consisting of a molecule each of ribophorins I and II and a nascent polypeptide chain. These observations suggest that the spiral form of polysomes could result from the forces generated by the extrusion of the growing polypeptide chains to one side of the polysome.

The presence of epidermal growth factor binding sites in the intracellular organelles of term human placenta

1986 ◽  
Vol 84 (1) ◽  
pp. 19-40
Author(s):  
N. Ramani ◽  
N. Chegini ◽  
C.V. Rao ◽  
P.G. Woost ◽  
G.S. Schultz
Keyword(s):  
Endoplasmic Reticulum ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Rough Endoplasmic Reticulum ◽  
Human Placenta ◽  
Binding Sites ◽  
Plasma Membranes ◽  
Smooth Endoplasmic Reticulum ◽  
Intracellular Organelles ◽  
Epidermal Growth

Highly purified lysosomes, rough and smooth endoplasmic reticulum, and Golgi apparatus, as well as microvillus plasma membranes, bound 125I-labelled epidermal growth factor ([125I]EGF) with similar affinity. Scatchard plots for all the organelles were curvilinear. The apparent number of available binding sites per mg protein of intracellular organelles was 27–71% of that found in microvillus plasma membranes. The bound and free [125I]EGF were not degraded by any of the organelles. Binding and dissociation of [125I]EGF in all organelles were dependent on the time and temperature of incubation. The specificity of [125I]EGF binding was similar in all organelles. The optimal pH for binding to lysosomes was 6.0, in contrast to 7.0 for all the other organelles. Exposure of different organelles to enzymes and protein-modifying reagents resulted in numerous binding differences between the intracellular organelles and microvillus plasma membranes. Covalent affinity labelling with [125I]EGF revealed two major proteins of 155 and 140(X10(3)) Mr in all the organelles. The 155 X 10(3) Mr protein was labelled predominantly in all organelles except rough endoplasmic reticulum, where both proteins were equally labelled. Addition of proteolytic inhibitors during isolation of organelles did not alter the pattern of [125I]EGF-labelled binding proteins found in the organelles. EGF also stimulated phosphorylation of the 155 and 140(X10(3)) Mr proteins in all the organelles. The 155 X 10(3) Mr protein was phosphorylated more than the 140 X 10(3) Mr protein in microvillus plasma membranes and smooth endoplasmic reticulum, whereas the 140 X 10(3) Mr protein was phosphorylated more than the 155 X 10(3) Mr protein in lysosomes and both proteins were equally phosphorylated in rough endoplasmic reticulum. Several organelles also contained minor [125I]EGF-binding proteins that did not show phosphorylation response and proteins that showed phosphorylation response but did not bind [125I]EGF. Thus, the present study demonstrates by a number of different criteria, that several intracellular organelles of term human placenta also contain EGF-binding and kinase activities.

scholarly journals The selectivity and stoicheiometry of membrane binding sites for polyribosomes, ribosomes and ribosomal subunits in vitro

1975 ◽  
Vol 146 (3) ◽  
pp. 513-526 ◽  
Author(s):  
T K Shires ◽  
C M McLaughlin ◽  
H C Pitot
Keyword(s):  
Endoplasmic Reticulum ◽  
Rough Endoplasmic Reticulum ◽  
Binding Sites ◽  
Large Subunit ◽  
Relative Concentration ◽  
Membrane Binding ◽  
Ribosomal Subunits ◽  
Derivatives Of ◽  
Membrane Binding Sites

Differences in the binding sites for polyribosomes, template-depleted ribosomes and large ribosomal subunits were found in microsomal derivatives of the rough endoplasmic reticulum. 1. The stoicheiometry of polyribosome and ribosome interaction in vitro with membranes was shown to be influenced by the relative concentration of interactants and the duration of their mixing. Large ribosomal subunits required a more prolonged mixing schedule to achieve saturation of membranes than did polyribosomes. 2. By using a procedure which minimized the effects on binidng by the stoicheiometric variables, competition between populations of polyribosomes, ribosomes and subunits for membrane sites showed that subunits, and to a lesser extent ribosomes, failed to block polyribosome attachment. 3. Polyribosomes isolated from liver, kidney and hepatoma 5123C entirely bound to a common membrane site, but some polyribosomes from myeloma MOPC-21 bound to other sites, perhaps influenced by their unique nascent proteins. 4. Subunit-binding sites appear on rough membranes only after endogenous polyribosomes have been removed, but no evidence that resulting changes in surface constituents are responsible was found. Large-subunit binding was largely abolished by lowering MgC12 concentration of 0.1 mM, whereas under the same conditions polyribosome binding was undiminished. 5. The large-subunit site appears to be distinct from the polyribosome site not only in the restriction of its affinity for particles but also spatially, to the extent that bound subunits do not hinder access of polyribosomes to their sites.

Association of glycoconjugates with the cytoskeletal framework

1983 ◽  
Vol 3 (4) ◽  
pp. 684-692
Author(s):  
A Ben-Ze'ev ◽  
R Abulafia
Keyword(s):  
Endoplasmic Reticulum ◽  
Rough Endoplasmic Reticulum ◽  
Nuclear Matrix ◽  
Binding Sites ◽  
Intact Cell ◽  
Lectin Binding ◽  
Fluorescent Antibody ◽  
Type I ◽  
Golgi System ◽  
Lectin Binding Sites

The association of glycoconjugates with the cytoskeletal framework was examined in detergent-extracted cells. Sparse cultures of fibroblasts that assemble only minimal amounts of extracellular matrix were extracted under mild conditions with Triton X-100 which remove most of the lipids and soluble cellular proteins. The detergent-resistant framework retains lectin binding sites in the nucleus, in the perinuclear area occupied by the rough endoplasmic reticulum-Golgi system of the intact cell, and in a network throughout the cytoskeletal framework. Fluorescent-antibody staining with antibody against collagen type I and fibronectin reveals extensive perinuclear staining of the remnant rough endoplasmic reticulum-Golgi system. In contrast, only sporadic staining of the pericellular area is obtained with these antibodies, in sparse cultures of whole cells. Lectin binding sites were detected in the nucleus and are attributed to chromatin-associated glycoconjugates. They can be removed by DNase under conditions that preserve the cytoplasmic lectin binding sites and the nuclear matrix. The results suggest a high degree of integration of the membrane residues of the cytoplasmic elements and the nuclear matrix with the skeletal framework and indicate a possible role for the glycoconjugates in this structural integration.

scholarly journals An immunocytochemical study of TSH beta storage in rat thyroidectomy cells with and without D or L thyroxine treatment.

1976 ◽  
Vol 24 (11) ◽  
pp. 1140-1149 ◽  
Author(s):  
G C Moriarty ◽  
R B Tobin
Keyword(s):  
Endoplasmic Reticulum ◽  
Rough Endoplasmic Reticulum ◽  
Binding Sites ◽  
Secretory Granules ◽  
Thyroid Stimulating Hormone ◽  
Immunocytochemical Staining ◽  
Immunocytochemical Study ◽  
Beta Chain ◽  
Thyroxine Treatment ◽  
Tsh Cells

Binding sites to the beta chain of thyroid stimulating hormone (TSH) were localized in pituitaries of thyroidectomized rats. Immunocytochemical staining was observed in hypertrophied TSH cells ("thyroidectomy cells") and primarily located in dilated rough endoplasmic reticulum. Staining was also found on the few secretory granules and on some of the intracisternal granules. Some of the thyroidectomy cells stained intensely, while others exhibited very little staining. When thyroidectomized rats were treated with thyroxine 4 days before death, the TSH cells contained more secretory granules, and the intracisternal granules were larger and more numerous. L-thyroxine was 10 times as potent as D-thyroxine in promoting the build-up of granules. Both types of granules stained intensely.

Sign in / Sign up

Export Citation Format

Share Document