scholarly journals Quantitative studies of pinocytosis. II. Kinetics of protein uptake and digestion by rat yolk sac cultured in vitro.

1975 ◽  
Vol 64 (1) ◽  
pp. 123-134 ◽  
Author(s):  
K E Williams ◽  
E M Kidston ◽  
F Beck ◽  
J B Lloyd
Keyword(s):  
Plasma Membrane ◽  
Initial Period ◽  
Yolk Sac ◽  
Membrane Receptors ◽  
Protein Uptake ◽  
Quantitative Studies ◽  
Intracellular Digestion ◽  
Visceral Yolk Sac ◽  
Plasma Membrane Receptors

Pinocytic uptake of 125I-labeled bovine serum albumin by 17.5-day rat visceral yolk sac cultured in vitro has been examined. Uptake was followed by intracellular digestion and, after an initial period, the content of radioactivity in the tissue itself remained constant during the incubation. Radiolabel was returned to the culture medium predominantly as (125I)iodotyrosine; exocytosis of undigested protein did not occur. The rate of uptake of labeled protein, which was constant within an experiment and reproducible between experiments, was much higher than that of a nondigestible macromolecule, 125I-labeled polyvinylpyrrolidone. The higher rate of uptake was a consequence of the protein entering the cells chiefly by adsorption to the plasma membrane being internalized; 125I-labeled albumin did not stimualte, nor did 125I-labeled polyvinylpyrrolidone inhibit pinocytosis. Different preparations of 125I-labeled albumin had characteristically different rates of uptake, probably reflecting differences in affinity for plasma membrane receptors. The physiological significance of the findings is discussed.

scholarly journals Neuronal L-Type Calcium Channel Signaling to the Nucleus Requires a Novel CaMKIIα-Shank3 Interaction

2019 ◽  
Author(s):  
Tyler L. Perfitt ◽  
Xiaohan Wang ◽  
Jason R. Stephenson ◽  
Terunaga Nakagawa ◽  
Roger J. Colbran
Keyword(s):  
Gene Expression ◽  
Plasma Membrane ◽  
Hippocampal Neurons ◽  
Molecular Mechanisms ◽  
Membrane Receptors ◽  
Scaffolding Protein ◽  
Downstream Signaling ◽  
Calcium Calmodulin Dependent ◽  
Plasma Membrane Receptors

ABSTRACTThe molecular mechanisms that couple plasma membrane receptors/channels to specific intracellular responses, such as increased gene expression, are incompletely understood. The postsynaptic scaffolding protein Shank3 associates with Ca2+ permeable receptors or ion channels that can activate many downstream signaling proteins, including calcium/calmodulin-dependent protein kinase II (CaMKII). Here, we show that Shank3/CaMKIIα complexes can be specifically co-immunoprecipitated from mouse forebrain lysates, and that purified activated (Thr286 autophosphorylated) CaMKIIα binds directly to Shank3 between residues 829-1130. Mutation of three basic residues in Shank3 (R949RK951) to alanine disrupts CaMKII binding to Shank3 fragments in vitro, as well as CaMKII association with full-length Shank3 in heterologous cells. Our shRNA/rescue studies revealed that Shank3 binding to both CaMKII and L-type calcium channels (LTCCs) is required for increased phosphorylation of the nuclear CREB transcription factor induced by depolarization of cultured hippocampal neurons. Thus, this novel Shank3-CaMKII interaction is essential for the initiation of a specific long-range signal from plasma membrane LTCCs to the nucleus that is required for activity-dependent changes in neuronal gene expression during learning and memory.

Sperm plasma membrane receptors for the porcine oocyte plasma membrane

Zygote ◽  
1998 ◽  
Vol 6 (2) ◽  
pp. 155-158 ◽  
Author(s):  
Miguel Betancourt ◽  
Yvonne Ducolomb ◽  
Irma Jiménez ◽  
Eduardo Casas ◽  
Edmundo Bonilla ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Membrane Receptors ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Calculated Concentration ◽  
Control Value ◽  
Molecular Events ◽  
Sperm Plasma Membrane ◽  
Plasma Membrane Receptors

In vitro fertilisation (IVF) was used to assess the ability of solubilised sperm plasma membrane (PM) proteins to inhibit the interaction of intact gametes. This is a first step before evaluating the ability of individual isolated proteins to competitively inhibit sperm-oocyte interaction as part of the process of studying the molecular events of fertilisation. Porcine oocytes were aspirated from ovaries, matured for 48 h in Medium 199, and the zona pellucida (ZP) was removed by exposure to acid Tyrode's solution. ZP-free matured oocytes were exposed to 200–800 μg/ml sperm PM protein for 1 h prior to insemination and during gamete co-incubation. Twenty-four hours after insemination with 5 × 105 capacitated sperm/ml, the oocytes were fixed, stained and examined. Sperm PM protein clearly inhibited IVF in a concentration-dependent manner (r = −0.87). The inhibition index (I50%), representing the sperm PM protein concentration necessary to inhibit IVF to 50% of the control value, was 310 µg/ml. These results demonstrate that solubilised sperm PM protein inhibits the interaction of intact gametes as one might expect for receptor-ligand interactions. Furthermore, the complement of sperm PM proteins appeared maximally effective at a calculated concentration of 690 µm/ml, providing a foundation for further studies with individual proteins.

scholarly journals Quantitative studies of pinocytosis. I. Kinetics of uptake of (125I)polyvinylpyrrolidone by rat yolk sac cultured in vitro.

1975 ◽  
Vol 64 (1) ◽  
pp. 113-122 ◽  
Author(s):  
K E Williams ◽  
E M Kidston ◽  
F Beck ◽  
J B Lloyd
Keyword(s):  
Electron Microscopy ◽  
In Vitro Culture ◽  
Quantitative Study ◽  
Light And Electron Microscopy ◽  
Yolk Sac ◽  
Quantitative Studies ◽  
Visceral Yolk Sac ◽  
Kinetics Of Uptake ◽  
Kinetics Of

A method is described for the in vitro culture of 17.5-day rat visceral yolk sac. Tissue survival was good as judged by light and electron microscopy. The rate of pinocytic uptake of 125I-labeled polyvinylpyrrolidone by the tissue was constant both within and between experiments. Within the concentration range 0.15-24 mug/ml, the 125I-labeled polyvinylpyrrolidone neither stimulated nor inhibited pinocytosis. The system offers many advantages in the quantitative study of the physical basis of pinocytosis.

scholarly journals Plasma membrane glycosphingolipid signaling: a turning point

2021 ◽  
Author(s):  
Elena Chiricozzi
Keyword(s):  
Plasma Membrane ◽  
Chemical Synthesis ◽  
Bioinformatic Analysis ◽  
Membrane Receptors ◽  
Outer Side ◽  
Neuronal Homeostasis ◽  
Extracellular Stimuli ◽  
Conceptual Shift ◽  
Plasma Membrane Receptors ◽  
Key Events

AbstractPlasma membrane interaction is highly recognized as an essential step to start the intracellular events in response to extracellular stimuli. The ways in which these interactions take place are less clear and detailed. Over the last decade my research has focused on developing the understanding of the glycosphingolipids-protein interaction that occurs at cell surface. By using chemical synthesis and biochemical approaches we have characterized some fundamental interactions that are key events both in the immune response and in the maintenance of neuronal homeostasis. In particular, for the first time it has been demonstrated that a glycolipid, present on the outer side of the membrane, the long-chain lactosylceramide, is able to directly modulate a cytosolic protein. But the real conceptual change was the demonstration that the GM1 oligosaccharide chain is able, alone, to replicate numerous functions of GM1 ganglioside and to directly interact with plasma membrane receptors by activating specific cellular signaling. In this conceptual shift, the development and application of multidisciplinary techniques in the field of biochemistry, from chemical synthesis to bioinformatic analysis, as well as discussions with several national and international colleagues have played a key role.

scholarly journals Effects of cytoplasmic acidification on clathrin lattice morphology.

1989 ◽  
Vol 108 (2) ◽  
pp. 401-411 ◽  
Author(s):  
J Heuser
Keyword(s):  
Plasma Membrane ◽  
Cultured Cells ◽  
Membrane Receptors ◽  
The Other ◽  
Culture Dish ◽  
Initial Curvature ◽  
Internal Ph ◽  
Cytoplasmic Acidification

Reducing the internal pH of cultured cells by several different protocols that block endocytosis is found to alter the structure of clathrin lattices on the inside of the plasma membrane. Lattices curve inward until they become almost spherical yet remain stubbornly attached to the membrane. Also, the lattices bloom empty "microcages" of clathrin around their edges. Correspondingly, broken-open cells bathed in acidified media demonstrate similar changes in clathrin lattices. Acidification accentuates the normal tendency of lattices to round up in vitro and also stimulates them to nucleate microcage formation from pure solutions of clathrin. On the other hand, several conditions that also inhibit endocytosis have been found to create, instead of unusually curved clathrin lattices with extraneous microcages, a preponderance of unusually flat lattices. These treatments include pH-"clamping" cells at neutrality with nigericin, swelling cells with hypotonic media, and sticking cells to the surface of a culture dish with soluble polylysine. Again, the unusually flat lattices in such cells display a tendency to round up and to nucleate clathrin microcage formation during subsequent in vitro acidification. This indicates that regardless of the initial curvature of clathrin lattices, they all display an ability to grow and increase their curvature in vitro, and this is enhanced by lowering ambient pH. Possibly, clathrin lattice growth and curvature in vivo may also be stimulated by a local drop in pH around clusters of membrane receptors.

Effect of yolk-sac antibody on rat embryos grown in culture

Development ◽  
1972 ◽  
Vol 27 (3) ◽  
pp. 543-553
Author(s):  
D. A. T. New ◽  
R. L. Brent
Keyword(s):  
Direct Contact ◽  
Culture Medium ◽  
Gamma Globulin ◽  
Yolk Sac ◽  
Amniotic Cavity ◽  
Pregnant Rats ◽  
Rat Embryos ◽  
Visceral Yolk Sac ◽  
Primary Action

Rat embryos, explanted with their embryonic membranes during the early stages of organogenesis ( days gestation), were grown in culture in roller tubes. Yolk-sac antibody (sheep anti rat yolk-sac gamma globulin), known to be teratogenic when injected into pregnant rats, was added to the culture medium. At concentrations of 0·1 mg/ml or more the antibody caused gross retardation of growth and differentiation. Injection of antibody into the amniotic cavity so that it had direct contact with the embryo, or between the amnion and yolk sac so that it was in contact with the mesodermal surface of the yolk sac, had little or no effect on development of the embryo or its membranes. These in vitro experiments indicate that yolk-sac antibody has an effect on development independent of any immunological reaction of the mother, and the primary action is probably on the visceral yolk-sac endoderm.

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