scholarly journals Identification of a novel Ca(2+)-regulated protein that is associated with the marginal band and centrosomes of chicken erythrocytes

1995 ◽  
Vol 108 (2) ◽  
pp. 685-698 ◽  
Author(s):  
J. Zhu ◽  
S.E. Bloom ◽  
E. Lazarides ◽  
C. Woods
Keyword(s):  
Sequence Analysis ◽  
Nuclear Membrane ◽  
Binding Sites ◽  
Cultured Cells ◽  
Marginal Band ◽  
Avian Erythrocyte ◽  
Chicken Erythrocytes ◽  
Definitive Erythropoiesis ◽  
Developmental Analysis

We have identified a novel Ca(2+)-regulated protein, p23, that is expressed specifically in avian erythrocyte and thrombocyte lineages. Sequence analysis of this 23 kDa protein reveals that it bears no homology to any known sequence. In mature definitive erythrocytes p23 exists in equilibrium between a soluble and a cytoskeletal bound pool. The cytoskeletal fraction is associated with the marginal band of microtubules, centrosomes and nuclear membrane under conditions of low free [Ca2+]. An increase in free [Ca2+] to 10(−6) M is sufficient to induce dissociation of > 95% of bound p23 from its target cytoskeletal binding sites, yet this [Ca2+] has little effect on calmodulin-mediated MB depolymerization. Analysis of p23 expression and localization during erythropoiesis together with results from heterologous p23 expression in tissue cultured cells demonstrated that this protein does not behave as a bone fide microtubule-associated protein. In addition, the developmental analysis revealed that although p23 is expressed early in definitive erythropoeisis, its association with the MB, centrosome and nuclear membrane occurs only in the final stages of differentiation. This cytoskeletal association correlates with marked p23 stabilization and accumulation at a time p23 expression is being markedly downregulated. We hypothesize that the mechanism of p23 association to the MB and centrosomes may be induced in part by a decrease in intracellular [Ca2+] during the terminal stages of definitive erythropoiesis.

scholarly journals A marginal band-associated protein has properties of both microtubule- and microfilament-associated proteins.

1989 ◽  
Vol 109 (4) ◽  
pp. 1609-1620 ◽  
Author(s):  
E Birgbauer ◽  
F Solomon
Keyword(s):  
Cultured Cells ◽  
Significant Proportion ◽  
Growth Cones ◽  
Dual Nature ◽  
Spatial Control ◽  
Marginal Band ◽  
Single Protein ◽  
Associated Proteins ◽  
Nonionic Detergent ◽  
Chicken Erythrocytes

The marginal band of nucleated erythrocytes is a microtubule organelle under rigorous quantitative and spatial control, with properties quite different from those of the microtubule organelles of cultured cells. Previous results suggest that proteins other than tubulin may participate in organizing the marginal band, and may interact with elements of the erythrocyte cytoskeleton in addition to microtubules. To identify such species, we raised mAbs against the proteins that assemble from chicken brain homogenates with tubulin. One such antibody binds to a single protein in chicken erythrocytes, and produces an immunofluorescence pattern colocalizing with marginal band microtubules. Several properties of this protein are identical to those of ezrin, a protein isolated from brush border and localized to motile elements of cultured cells. A significant proportion of the antigen is not soluble in erythrocytes, as determined by extraction with nonionic detergent. This cytoskeleton-associated fraction is unaffected by treatments that solubilize the marginal band microtubules. The protein has properties of both microtubule- and microfilament-associated proteins. In the accompanying manuscript (Goslin, K., E. Birgbauer, G. Banker, and F. Solomon. 1989. J. Cell Biol. 109:1621-1631), we show that the same antibody recognizes a component of growth cones with a similar dual nature. In early embryonic red blood cells, the antigen is dispersed throughout the cell and does not colocalize with assembled tubulin. Its confinement to the marginal band during development follows rather than precedes that of microtubules. These results, along with previous work, suggest models for the formation of the marginal band.

scholarly journals Localization of Antibody-Binding Sites by Sequence Analysis of Cloned Pilin Genes from Neisseria Gonorrhoeae

Microbiology ◽  
1987 ◽  
Vol 133 (4) ◽  
pp. 825-833 ◽  
Author(s):  
I. J. Nicolson ◽  
A. C. F. Perry ◽  
M. Virji ◽  
J. E. Heckels ◽  
J. R. Saunders
Keyword(s):  
Sequence Analysis ◽  
Neisseria Gonorrhoeae ◽  
Binding Sites ◽  
Antibody Binding

Elicitor-binding proteins and signal transduction in the activation of a phytoalexin defense response

1995 ◽  
Vol 73 (S1) ◽  
pp. 506-510 ◽  
Author(s):  
Jürgen Ebel ◽  
Markus Feger ◽  
Ulrich Kissel ◽  
Axel Mithöfer ◽  
Tom Waldmüller ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Glycine Max ◽  
Defense Response ◽  
Binding Sites ◽  
Binding Proteins ◽  
Cultured Cells ◽  
Phytophthora Sojae ◽  
Phytophthora Megasperma ◽  
Early Stages ◽  
Signalling Process

Inducible plant defenses against potential pathogens are thought to be activated by signal compounds released during early stages of the infection process. In the incompatible interaction between soybean (Glycine max L.) and the oomycete Phytophthora megasperma f.sp. glycinea (= Phytophthora sojae) a rapid, localized phytoalexin response is activated at the level of transcription. The phytoalexin response is also stimulated in various soybean tissues, including cultured cells, following treatment with an elicitor derived from the cell walls of the fungus. The best characterized elicitors of P. megasperma for soybean are the branched (1→3)- and (1→6)-linked β-glucans, structural polysaccharides of the hyphal walls. The glucans are naturally released during the early stages of germination of the fungal cysts in a host-independent manner. Cyclic β-glucans of Bradyrhizobium japonicum USDA 110, a symbiont of soybean, arc not active in inducing phytoalexin production in soybean. When tested in combination, B. japonicum β-glucans inhibited stimulation of phytoalexin accumulation by the fungal glucans. Surface-localized glucan-binding proteins exist in soybean cells that display high affinity and specificity for the fungal β-glucans, including an elicitor-active hepta-β-glucoside fragment derived from the polysaccharide, suggesting that elicitor action involves a transmembrane signalling process. The main component of the soybean β-glucan binding sites appears to be a 70-kDa protein. Hepta-β-glucoside binding sites exist in several other legumes, such as bean (Phaseolus vulgaris L.), pea (Pisum sativum L.), and lupine (Lupinus albus L.). The signalling process initiated by the β-glucan elicitor, which leads to the activation of the phytoalexin defense response in soybean, involves changes in the permeability of the plasma membrane to Ca2+ and H+. Chloride channel antagonists are more efficient than calcium channel antagonists in inhibiting both the phytoalexin response and the inducible ion fluxes. The results present evidence that the observed permeability changes of the plasma membrane are primary events in the transduction of the elicitor signal(s) by the challenged soybean cells. Key words: soybean (Glycine max), Phytophthora megasperma f.sp. glycinea, β-glucan elicitor, elicitor-binding proteins, phytoalexins, Ca2+.

Sequence Analysis of Fis Binding Sites Obtained by in Vitro Selection

1997 ◽  
Vol 16 (5-6) ◽  
pp. 579-584
Author(s):  
Karsten Theis ◽  
Cornelia Bartsch ◽  
Wolfram Saenger
Keyword(s):  
Sequence Analysis ◽  
Binding Sites ◽  
In Vitro Selection

Transcriptional regulation of human SREBP-1c (sterol-regulatory-element-binding protein-1c): a key regulator of lipogenesis

2004 ◽  
Vol 32 (1) ◽  
pp. 107-109 ◽  
Author(s):  
E. Tarling ◽  
A. Salter ◽  
A. Bennett
Keyword(s):  
Transcription Factor ◽  
Sequence Analysis ◽  
Binding Sites ◽  
Binding Protein ◽  
Regulatory Element ◽  
Transcription Factor Binding Sites ◽  
Transcription Factor Binding ◽  
Factor Binding ◽  
Element Binding Protein ◽  
Sterol Regulatory Element

Sterol-regulatory-element-binding protein 1c (SREBP-1c) is one member of the family of transcription factors that stimulate sterol and fatty-acid biosynthesis in animal cells. Human SREBP-1c, mapped to chromosome 17p11.2, is expressed in liver, intestine, skeletal muscle and adipocytes. A section of genomic sequence from a chromosome 17 library, thought to contain the SREBP-1c promoter, was cloned. Putative transcription-factor-binding sites and a potential transcriptional start site were identified using the Genomatix Suite of sequence analysis tools (MatInspector®). Sequence analysis showed the human promoter to be 42% identical with the previously published mouse sequence. Two novel transcription-factor-binding sites were identified: those for PDX-1 (pancreatic–duodenal homoeobox-1) and HNF-4 (hepatic nuclear factor-4). Co-transfection experiments with overexpression plasmids for PDX-1 and HNF-4 suggested that both factors stimulate SREBP-1c gene expression, although further work is required to ascertain their mechanisms of action.

scholarly journals Induction of a Massive Endoplasmic Reticulum and Perinuclear Space Expansion by Expression of Lamin B Receptor Mutants and the Related Sterol Reductases TM7SF2 and DHCR7

2010 ◽  
Vol 21 (2) ◽  
pp. 354-368 ◽  
Author(s):  
Monika Zwerger ◽  
Thorsten Kolb ◽  
Karsten Richter ◽  
Iakowos Karakesisoglou ◽  
Harald Herrmann
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
Cell Lines ◽  
Nuclear Membrane ◽  
Cultured Cells ◽  
Membrane Separation ◽  
Reductase Activity ◽  
Nuclear Pore ◽  
Lamin B ◽  
Lamin B Receptor

Lamin B receptor (LBR) is an inner nuclear membrane protein involved in tethering the nuclear lamina and the underlying chromatin to the nuclear envelope. In addition, LBR exhibits sterol reductase activity. Mutations in the LBR gene cause two different human diseases: Pelger-Huët anomaly and Greenberg skeletal dysplasia, a severe chrondrodystrophy causing embryonic death. Our study aimed at investigating the effect of five LBR disease mutants on human cultured cells. Three of the tested LBR mutants caused a massive compaction of chromatin coincidental with the formation of a large nucleus-associated vacuole (NAV) in several human cultured cell lines. Live cell imaging and electron microscopy revealed that this structure was generated by the separation of the inner and outer nuclear membrane. During NAV formation, nuclear pore complexes and components of the linker of nucleoskeleton and cytoskeleton complex were lost in areas of membrane separation. Concomitantly, a large number of smaller vacuoles formed throughout the cytoplasm. Notably, forced expression of the two structurally related sterol reductases transmembrane 7 superfamily member 2 and 7-dehydrocholesterol reductase caused, even in their wild-type form, a comparable phenotype in susceptible cell lines. Hence, LBR mutant variants and sterol reductases can severely interfere with the regular organization of the nuclear envelope and the endoplasmic reticulum.

PGE2 binding sites and PG-stimulated cyclic AMP accumulation in rat isolated glomeruli and glomerular cultured cells

1983 ◽  
Vol 30 (2) ◽  
pp. 201-214 ◽  
Author(s):  
Gérard Friedlander ◽  
Dominique Chansel ◽  
Josée Sraer ◽  
Marcelle Bens ◽  
Raymond Ardaillou
Keyword(s):  
Cyclic Amp ◽  
Binding Sites ◽  
Cultured Cells ◽  
Isolated Glomeruli ◽  
Cyclic Amp Accumulation
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