Visualization of the membrane bound cytoskeleton and coated pits of plant cells by means of dry cleaving

PROTOPLASMA ◽  
1984 ◽  
Vol 119 (3) ◽  
pp. 212-218 ◽  
Author(s):  
J. A. Traas
Keyword(s):  
Plant Cells ◽  
Coated Pits ◽  
Membrane Bound ◽  
Dry Cleaving

Pyrophosphate as an alternative energy currency in plants

2021 ◽  
Vol 478 (8) ◽  
pp. 1515-1524
Author(s):  
Abir U. Igamberdiev ◽  
Leszek A. Kleczkowski
Keyword(s):  
Metabolic Pathways ◽  
Energy Efficient ◽  
Alternative Energy ◽  
Plant Cells ◽  
Atp Synthesis ◽  
Continuous Operation ◽  
Low Oxygen ◽  
Pyruvate Phosphate Dikinase ◽  
Oxygen Stress ◽  
Membrane Bound

In the conditions of [Mg2+] elevation that occur, in particular, under low oxygen stress and are the consequence of the decrease in [ATP] and increase in [ADP] and [AMP], pyrophosphate (PPi) can function as an alternative energy currency in plant cells. In addition to its production by various metabolic pathways, PPi can be synthesized in the combined reactions of pyruvate, phosphate dikinase (PPDK) and pyruvate kinase (PK) by so-called PK/PPDK substrate cycle, and in the reverse reaction of membrane-bound H+-pyrophosphatase, which uses the energy of electrochemical gradients generated on tonoplast and plasma membrane. The PPi can then be consumed in its active forms of MgPPi and Mg2PPi by PPi-utilizing enzymes, which require an elevated [Mg2+]. This ensures a continuous operation of glycolysis in the conditions of suppressed ATP synthesis, keeping metabolism energy efficient and less dependent on ATP.

scholarly journals Polarized compartmentalization of organelles in growth cones from developing optic tectum.

1985 ◽  
Vol 101 (4) ◽  
pp. 1473-1480 ◽  
Author(s):  
T P Cheng ◽  
T S Reese
Keyword(s):  
Endoplasmic Reticulum ◽  
Growth Cone ◽  
Smooth Endoplasmic Reticulum ◽  
Freeze Substitution ◽  
Growth Cones ◽  
Distal Segment ◽  
Computer Assisted ◽  
Chemical Fixation ◽  
Coated Pits ◽  
Membrane Bound

We have used computer-assisted reconstructions of continuous serial sections to study the cytoplasmic organization of growth cones in vivo. Optic tecta from 6.25-6.5-d-old chicken embryos were quick-frozen and then freeze-substituted in acetone-osmium tetroxide or, for comparison, prepared by conventional fixation. Images of eight freeze-substituted and two conventionally fixed growth cones were reconstructed from aligned serial micrographs. After freeze-substitution, numerous lumenless membrane-bound sacs arrayed in multilamellar stacks appear to replace the abundant smooth endoplasmic reticulum found after chemical fixation. Microtubule fascicles progressively diverge from their typical fascicular organization in the initial segment of the growth cone and are absent in the varicosity and the more distal segment. Mitochondria, in contrast, are concentrated in the proximal segment of the varicosity; multilamellar stacks and endosome-like vacuoles are in the distal segment; and coated pits and vesicles are concentrated near the terminal filopodium, which is the most distal and organelle-poor domain of the growth cone. These observations suggest that dilation and fusion of the lumenless, membrane-bound sacs that occurs during chemical fixation give rise to the network of smooth endoplasmic reticulum. The three-dimensional reconstructions show that the cytoplasmic components of growth cones, including the membrane-bound sacs and multilamellar stacks revealed by freeze substitution, are polarized along the axis of these growth cones, which suggests that they have a role in recycling of membrane during elongation of the growth cone.

scholarly journals Role of plasma-membrane-bound sialidase NEU3 in clathrin-mediated endocytosis

2015 ◽  
Vol 470 (1) ◽  
pp. 131-144 ◽  
Author(s):  
Macarena Rodriguez-Walker ◽  
Aldo A. Vilcaes ◽  
Eduardo Garbarino-Pico ◽  
José L. Daniotti
Keyword(s):  
Plasma Membrane ◽  
Subcellular Distribution ◽  
Cellular Functions ◽  
Coated Pits ◽  
Key Enzyme ◽  
Membrane Bound

Sialidase NEU3 is a key enzyme in the catabolism of gangliosides. We demonstrated that NEU3 impairs cargo internalization via clathrin-coated pits, affecting AP-2 subcellular distribution. This study delineates previously unidentified cellular functions of NEU3.

scholarly journals The effect of diffusion on the binding of membrane-bound receptors to coated pits

1985 ◽  
Vol 47 (1) ◽  
pp. 79-87 ◽  
Author(s):  
J. Keizer ◽  
J. Ramirez ◽  
E. Peacock-López
Keyword(s):  
Coated Pits ◽  
Membrane Bound

scholarly journals A Review of Plant Vacuoles: Formation, Located Proteins, and Functions

Plants ◽  
2019 ◽  
Vol 8 (9) ◽  
pp. 327 ◽  
Author(s):  
Xiaona Tan ◽  
Kaixia Li ◽  
Zheng Wang ◽  
Keming Zhu ◽  
Xiaoli Tan ◽  
...  
Keyword(s):  
Growth And Development ◽  
Plant Cells ◽  
Cellular Membrane ◽  
Growth Conditions ◽  
Environmental Stability ◽  
Cell Type ◽  
Different Types ◽  
Plant Vacuoles ◽  
Membrane Bound ◽  
Multiple Signaling

Vacuoles, cellular membrane-bound organelles, are the largest compartments of cells, occupying up to 90% of the volume of plant cells. Vacuoles are formed by the biosynthetic and endocytotic pathways. In plants, the vacuole is crucial for growth and development and has a variety of functions, including storage and transport, intracellular environmental stability, and response to injury. Depending on the cell type and growth conditions, the size of vacuoles is highly dynamic. Different types of cell vacuoles store different substances, such as alkaloids, protein enzymes, inorganic salts, sugars, etc., and play important roles in multiple signaling pathways. Here, we summarize vacuole formation, types, vacuole-located proteins, and functions.

The effect of diffusion on the trapping of membrane-bound receptors by localized coated pits

1986 ◽  
Vol 25 (2) ◽  
pp. 117-125 ◽  
Author(s):  
Enrique Peacock-Lopez ◽  
Jose Antonio Ramirez
Keyword(s):  
Coated Pits ◽  
Membrane Bound

Endocytosis, intracellular transport, and cytotoxic action of Shiga toxin and ricin

1996 ◽  
Vol 76 (4) ◽  
pp. 949-966 ◽  
Author(s):  
K. Sandvig ◽  
B. van Deurs
Keyword(s):  
Shiga Toxin ◽  
Intracellular Transport ◽  
Retrograde Transport ◽  
Cytotoxic Action ◽  
Coated Pits ◽  
Polarized Epithelia ◽  
Protein Toxins ◽  
A Cell ◽  
Membrane Bound ◽  
Golgi Network

Protein toxins such as ricin and Shiga toxin with intracellular targets have to be endocytosed and translocated to the cytosol to inhibit the protein synthesis and thereby kill the cell. Ricin is internalized by both clathrin-dependent and -independent endocytic mechanisms, whereas Shiga toxin seems to be taken up exclusively from clathrin-coated pits. After endocytosis, internalized membrane and content are delivered to endosomes, where sorting for further routing in the cell takes place. Toxins that remain membrane bound at low endosomal pH can be recycled to the cell surface or transcytosed in polarized epithelia. A large proportion of internalized toxin is transported to lysosomes for degradation. Most importantly, a fraction of the internalized ricin and Shiga toxin molecules is delivered to the trans-Golgi network (TGN). Shiga toxin can, in some very sensitive cells, be transported retrogradely through the Golgi cisterns all the way back to the endoplasmic reticulum (ER), and it is possible that also ricin is transported retrogradely to the ER. In this review, a cell biological overview of these intracellular transport steps is presented, and evidence is provided that the delivery to the TGN and the subsequent retrograde transport to the ER are required for optimal intoxication. Moreover, it is argued that knowledge of this transport is important for targeted drug delivery such as the application of immunotoxins in cancer therapy.

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