Microtubular-marginal band in the avian erythrocyte: Studies of cell swelling kinetics and identification of tubulin-binding proteins of plasma membrane skeleton which co-localize with the microtubular marginal band

1991 ◽  
Author(s):  
F. Stetzkowski-Marden ◽  
C. Deprette ◽  
R. Cassoly
Keyword(s):  
Plasma Membrane ◽  
Binding Proteins ◽  
Membrane Skeleton ◽  
Cell Swelling ◽  
Swelling Kinetics ◽  
Tubulin Binding ◽  
Marginal Band ◽  
Avian Erythrocyte

scholarly journals Ultrastructure of the yeast actin cytoskeleton and its association with the plasma membrane.

1994 ◽  
Vol 125 (2) ◽  
pp. 381-391 ◽  
Author(s):  
J Mulholland ◽  
D Preuss ◽  
A Moon ◽  
A Wong ◽  
D Drubin ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Actin Cytoskeleton ◽  
Binding Proteins ◽  
Ultrastructural Level ◽  
Actin Binding ◽  
Cortical Actin ◽  
Actin Binding Proteins ◽  
Double Labeling ◽  
Wall Growth ◽  
Cortical Cytoskeleton

We characterized the yeast actin cytoskeleton at the ultrastructural level using immunoelectron microscopy. Anti-actin antibodies primarily labeled dense, patchlike cortical structures and cytoplasmic cables. This localization recapitulates results obtained with immunofluorescence light microscopy, but at much higher resolution. Immuno-EM double-labeling experiments were conducted with antibodies to actin together with antibodies to the actin binding proteins Abp1p and cofilin. As expected from immunofluorescence experiments, Abp1p, cofilin, and actin colocalized in immuno-EM to the dense patchlike structures but not to the cables. In this way, we can unambiguously identify the patches as the cortical actin cytoskeleton. The cortical actin patches were observed to be associated with the cell surface via an invagination of plasma membrane. This novel cortical cytoskeleton-plasma membrane interface appears to consist of a fingerlike invagination of plasma membrane around which actin filaments and actin binding proteins are organized. We propose a possible role for this unique cortical structure in wall growth and osmotic regulation.

scholarly journals Penicillin-binding proteins and carboxypeptidase/transpeptidase activities in Proteus vulgaris P18 and its penicillin-induced stable L-forms

1982 ◽  
Vol 152 (3) ◽  
pp. 1042-1048
Author(s):  
A Rousset ◽  
M Nguyen-Distèche ◽  
R Minck ◽  
J M Ghuysen
Keyword(s):  
Plasma Membrane ◽  
Binding Proteins ◽  
Binding Protein ◽  
Penicillin Binding Protein ◽  
Proteus Vulgaris ◽  
Penicillin Binding Proteins

The originally penicillin-induced, wall-less stable L-forms of Proteus vulgaris P18, isolated by Tulasne in 1949 and since then cultured in he absence of penicillin, have kept the ability to synthesize the seven penicillin-binding proteins and the various DD- and LD-peptidase activities found in the parental bacteria and known to be involved in wall peptidoglycan metabolism. The stable L-forms, however, secrete during growth both the highly penicillin-sensitive, DD-carboxy-peptidase-transpeptidase penicillin-binding protein PBP4 (which in normal bacteria is relatively loosely bound to the plasma membrane) and the penicillin-insensitive LD-carboxypeptidase (which in normal bacteria is located in the periplasmic region).

The preparation and ultrastructure of avian erythrocyte nuclear envelope enclosed by the plasma membrane

1978 ◽  
Vol 34 (1) ◽  
pp. 81-90
Author(s):  
J.R. Harris
Keyword(s):  
Plasma Membrane ◽  
Nuclear Envelope ◽  
Ammonium Molybdate ◽  
Negative Staining ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Thin Sectioning ◽  
Avian Erythrocyte ◽  
Pore Complexes ◽  
Low Ionic Strength

A procedure is described for the preparation of avian erythrocyte nuclear envelope ghosts which remain enclosed by the ellipsoid plasma membrane. Haemoglobin-free nucleated chicken erythrocyte ghosts are treated in a low ionic strength buffer plus heparin which brings about decondensation of the chromatin. This is followed by solubilization of the chromatin by digestion with pancreatic deoxyribonuclease-1. When studied by light microscopy using either phase-contrast or Nomarski interference optics, the ellipsoid plasma membrane is clearly seen to remain with the collapsed nuclear envelope trapped inside. This interpretation is supported by negative-staining electron microscopy using ammonium molybdate, which in addition reveals the presence of the nuclear pore complexes. The suggestion is advanced that structural protection is provided for the fragile nuclear envelope system by the surrounding plasma membrane, which might account for the final nuclear envelope being in the form of relatively intact ghosts with well defined nuclear pore complexes. The nuclear envelope is highly fragmented when the plasma membrane is absent, the nuclear pore complexes showing appreciable breakdown. Thin sectioning supports the results of negative staining and in addition shows the nuclear envelope retained within the plasma membrane to be composed of both inner and outer nuclear membranes, but the nuclear pore complexes are not clearly defined.

Activation of the small GTP-binding proteins rho and rac by growth factor receptors

1995 ◽  
Vol 108 (1) ◽  
pp. 225-233 ◽  
Author(s):  
C.D. Nobes ◽  
P. Hawkins ◽  
L. Stephens ◽  
A. Hall
Keyword(s):  
Plasma Membrane ◽  
Growth Factor ◽  
Tyrosine Kinase ◽  
Phorbol Ester ◽  
Lysophosphatidic Acid ◽  
Actin Polymerization ◽  
Binding Proteins ◽  
Platelet Derived Growth Factor ◽  
Gtp Binding ◽  
Rho Protein

The small GTP-binding proteins, rho and rac, control signal transduction pathways that link growth factor receptors to the activation of actin polymerization. In Swiss 3T3 cells, rho proteins mediate the lysophosphatidic acid and bombesin-induced formation of focal adhesions and actin stress fibres, whilst rac proteins are required for the platelet-derived growth factor-, insulin-, bombesin- and phorbol ester (phorbol 12-myristate 13-acetate)-stimulated actin polymerization at the plasma membrane that results in membrane ruffling. To investigate the role of p85/p110 phosphatidylinositol 3-kinase in the rho and rac signalling pathways, we have used a potent inhibitor of this activity, wortmannin. Wortmannin has no effect on focal adhesion or actin stress fibre formation induced by lysophosphatidic acid, bombesin or microinjected recombinant rho protein. In contrast, it totally inhibits plasma membrane edge-ruffling induced by platelet-derived growth factor and insulin though not by bombesin, phorbol ester or microinjected recombinant rac protein. We conclude that phosphatidylinositol 3,4,5 trisphosphate mediates activation of rac by the platelet-derived growth factor and insulin receptors. The effects of lysophosphatidic acid on the Swiss 3T3 actin cytoskeleton can be blocked by the tyrosine kinase inhibitor, tyrphostin. Since tyrphostin does not inhibit the effects of microinjected rho protein, we conclude that lysophosphatidic acid activation of rho is mediated by a tyrosine kinase.

Inhibition of sperm-egg fusion in the hamster and mouse by carbohydrates

Zygote ◽  
1994 ◽  
Vol 2 (3) ◽  
pp. 253-262 ◽  
Author(s):  
Ruben H. Ponce ◽  
Umbert A. Urch ◽  
Ryuzo Yanagimachi
Keyword(s):  
Extracellular Matrix ◽  
Plasma Membrane ◽  
Zona Pellucida ◽  
Binding Proteins ◽  
Toxic Effects ◽  
Carbohydrate Binding ◽  
Dextran Sulphate ◽  
Membrane Glycoproteins ◽  
Carbohydrate Binding Proteins

SummaryAfter spermatozoa bind to and penetrate the extracellular matrix of the egg, the zona pellucida, they adhere to and fuse with the plasma membrane of the egg. Since sperm–egg fusion may involve membrane glycoproteins and/or carbohydrate binding proteins, we sought to test this hypothesis by challenging sperm–egg fusion in hamster and in mouse with added carbohydrates. In this study, a number of carbohydrate and glycoconjugates were examined for their ability to inhibit sperm–eggfusion. In the hamster, D(+)-glucosamine, D(+)-galactosamine, albumin-bovine-glucosamide and-galactosamide, fucoidan and dextran sulphate inhibited the fusion of spermatozoa with zona-free eggs. The same effects were seen in the mouse, except for the toxic effects of D(+)-galactosamine. These facts suggest a role of carbohydrate binding proteins or glycoproteins in the fertilisation process at the level of binding to and fusing with the oolemma.

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+.

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