scholarly journals Functional Symmetry of Endomembranes

2007 ◽  
Vol 18 (4) ◽  
pp. 1430-1436 ◽  
Author(s):  
Jaakko Saraste ◽  
Bruno Goud
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Cell Activation ◽  
Membrane System ◽  
Eukaryotic Cells ◽  
Membrane Recycling ◽  
Major Task ◽  
Late Endosomes ◽  
Intermediate Compartment ◽  
Functional Symmetry

In higher eukaryotic cells pleiomorphic compartments composed of vacuoles, tubules and vesicles move from the endoplasmic reticulum (ER) and the plasma membrane to the cell center, operating in early biosynthetic trafficking and endocytosis, respectively. Besides transporting cargo to the Golgi apparatus and lysosomes, a major task of these compartments is to promote extensive membrane recycling. The endocytic membrane system is traditionally divided into early (sorting) endosomes, late endosomes and the endocytic recycling compartment (ERC). Recent studies on the intermediate compartment (IC) between the ER and the Golgi apparatus suggest that it also consists of peripheral (“early”) and centralized (“late”) structures, as well as a third component, designated here as the biosynthetic recycling compartment (BRC). We propose that the ERC and the BRC exist as long-lived “mirror compartments” at the cell center that also share the ability to expand and become mobilized during cell activation. These considerations emphasize the functional symmetry of endomembrane compartments, which provides a basis for the membrane rearrangements taking place during cell division, polarization, and differentiation.

scholarly journals cis-Golgi proteins accumulate near the ER exit sites and act as the scaffold for Golgi regeneration after brefeldin A treatment in tobacco BY-2 cells

2012 ◽  
Vol 23 (16) ◽  
pp. 3203-3214 ◽  
Author(s):  
Yoko Ito ◽  
Tomohiro Uemura ◽  
Keiko Shoda ◽  
Masaru Fujimoto ◽  
Takashi Ueda ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Fluorescent Proteins ◽  
Plant Cells ◽  
Brefeldin A ◽  
Eukaryotic Cells ◽  
Er Exit Sites ◽  
Intermediate Compartment ◽  
Golgi Protein ◽  
And Function

The Golgi apparatus forms stacks of cisternae in many eukaryotic cells. However, little is known about how such a stacked structure is formed and maintained. To address this question, plant cells provide a system suitable for live-imaging approaches because individual Golgi stacks are well separated in the cytoplasm. We established tobacco BY-2 cell lines expressing multiple Golgi markers tagged by different fluorescent proteins and observed their responses to brefeldin A (BFA) treatment and BFA removal. BFA treatment disrupted cis, medial, and trans cisternae but caused distinct relocalization patterns depending on the proteins examined. Medial- and trans-Golgi proteins, as well as one cis-Golgi protein, were absorbed into the endoplasmic reticulum (ER), but two other cis-Golgi proteins formed small punctate structures. After BFA removal, these puncta coalesced first, and then the Golgi stacks regenerated from them in the cis-to-trans order. We suggest that these structures have a property similar to the ER-Golgi intermediate compartment and function as the scaffold of Golgi regeneration.

scholarly journals The amounts and rates of export of polysaccharides found within the membrane system of maize root cells

1974 ◽  
Vol 142 (1) ◽  
pp. 139-144 ◽  
Author(s):  
Dianna J. Bowles ◽  
D. H. Northcote
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Golgi Apparatus ◽  
Cell Surface ◽  
Rough Endoplasmic Reticulum ◽  
Membrane System ◽  
Maize Root ◽  
Wall Material ◽  
Cell Wall Material ◽  
Root Cells

1. Maize seedling roots were incubated in vivo with d-[U-14C]glucose for 2, 5, 10, 15, 30 and 45min. The total incorporation of radioactivity into polysaccharide components in isolated fractions was investigated, and the pattern of incorporation into different polysaccharide components within the rough endoplasmic reticulum, Golgi apparatus and exported material was analysed. 2. The membrane compartments reached a saturation value of radioactivity in polysaccharide components by 30min incubation. Radioactivity in exported polysaccharide continued to increase after that time. The latter was formed and maintained by a steady-state turnover of polysaccharide synthesis and transport from the membrane system. 3. If the only access of the slime polysaccharide to the cell surface is via dictyosome-derived vesicles, the amount of slime components in the Golgi apparatus would have to be displaced every 0.3min in order to maintain the observed rates of increase in slime. This is in contrast with a displacement time of about 2.5min that is necessary for polysaccharide components in the Golgi apparatus to produce the observed increase in cell-wall material. The activity of the membrane system in the production of maize root slime is 8 times as great as that of the membrane system involved in cell-wall synthesis. 4. If the amount of polysaccharide material in the Golgi apparatus is maintained only by inflow of polymeric material from the rough endoplasmic reticulum the total amount of slime components in the rough endoplasmic reticulum would have to be displaced every 7min to maintain a constant amount in the Golgi apparatus. If the endoplasmic reticulum contributed directly to the cell surface in the synthesis of cell-wall material, displacement times necessary to maintain the observed rate of polymer production would be very slow.

scholarly journals The Discovery and History of Animal and Human Physiology

2020 ◽  
Vol 1 (6) ◽  
pp. 19-27
Author(s):  
Guirad Oth ◽  
Yrick John
Keyword(s):  
Endoplasmic Reticulum ◽  
Human Physiology ◽  
Cell Nucleus ◽  
Membrane System ◽  
Eukaryotic Cells ◽  
History Of ◽  
Nucleus Structure

This study discusses Nucleus, history of the discovery of the cell nucleus Structure and parts of the cell nucleus. All of them is the phisiology of animal and human. The cell nucleus (nucleus) can be defined as an organelle found in eukaryotic cells. Nucleoplasm The nucleoplasm is the liquid that is in the nucleus which is thick and transparent. The cell nucleus has many genes from DNA which are arranged and form structures called chromosomes. The endoplasmic reticulum consists of tubules, vesicles and flattened pockets that occupy the cytoplasmic space. The endoplasmic reticulum is a part of the cell that consists of a membrane system, which has a structure that resembles a multi-layered sac. These sacs are called cisternae.

scholarly journals The Golgi Apparatus Maintains Its Organization Independent of the Endoplasmic Reticulum

2006 ◽  
Vol 17 (12) ◽  
pp. 5372-5380 ◽  
Author(s):  
Matthew Y. Pecot ◽  
Vivek Malhotra
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Binding Protein ◽  
Physiological Conditions ◽  
Fk506 Binding Protein ◽  
Golgi Membranes ◽  
Intermediate Compartment ◽  
Tight Association

Under artificial conditions Golgi enzymes have the capacity to rapidly accumulate in the endoplasmic reticulum (ER). These observations prompted the idea that Golgi enzymes constitutively recycle through the ER. We have tested this hypothesis under physiological conditions through use of a procedure that captures Golgi enzymes in the ER. In the presence of rapamycin, which induces a tight association between FKBP (FK506-binding protein) and FRAP (FKBP-rapamycin–associated protein), an FKBP-tagged Golgi enzyme can be trapped when it visits the ER by an ER-retained protein fused to FRAP. We find that although FKBP-ERGIC-53 of the ER-Golgi intermediate compartment (ERGIC) rapidly cycles through the ER (30 min), FKBP-Golgi enzyme chimeras remain stably associated with Golgi membranes. We also demonstrate that Golgi dispersion upon nocodazole treatment mainly occurs through a mechanism that does not involve the recycling of Golgi membranes through the ER. Our findings suggest that the Golgi apparatus, as defined by its collection of resident enzymes, exists independent of the ER.

scholarly journals The Mammalian Protein (rbet1) Homologous to Yeast Bet1p Is Primarily Associated with the Pre-Golgi Intermediate Compartment and Is Involved in Vesicular Transport from the Endoplasmic Reticulum to the Golgi Apparatus

1997 ◽  
Vol 139 (5) ◽  
pp. 1157-1168 ◽  
Author(s):  
Tao Zhang ◽  
Siew Heng Wong ◽  
Bor Luen Tang ◽  
Yue Xu ◽  
Frank Peter ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
G Protein ◽  
Vesicular Transport ◽  
Dependent Manner ◽  
Golgi Transport ◽  
Golgi Region ◽  
Intermediate Compartment ◽  
Kdel Receptor ◽  
Mammalian Protein

Yeast Bet1p participates in vesicular transport from the endoplasmic reticulum to the Golgi apparatus and functions as a soluble N-ethylmaleimide–sensitive factor attachment protein receptor (SNARE) associated with ER-derived vesicles. A mammalian protein (rbet1) homologous to Bet1p was recently identified, and it was concluded that rbet1 is associated with the Golgi apparatus based on the subcellular localization of transiently expressed epitope-tagged rbet1. In the present study using rabbit antibodies raised against the cytoplasmic domain of rbet1, we found that the majority of rbet1 is not associated with the Golgi apparatus as marked by the Golgi mannosidase II in normal rat kidney cells. Rather, rbet1 is predominantly associated with vesicular spotty structures that concentrate in the peri-Golgi region but are also present throughout the cytoplasm. These structures colocalize with the KDEL receptor and ERGIC-53, which are known to be enriched in the intermediate compartment. When the Golgi apparatus is fragmented by nocodazole treatment, a significant portion of rbet1 is not colocalized with structures marked by Golgi mannosidase II or the KDEL receptor. Association of rbet1 in cytoplasmic spotty structures is apparently not altered by preincubation of cells at 15°C. However, upon warming up from 15 to 37°C, rbet1 concentrates into the peri-Golgi region. Furthermore, rbet1 colocalizes with vesicular stomatitis virus G-protein en route from the ER to the Golgi. Antibodies against rbet1 inhibit in vitro transport of G-protein from the ER to the Golgi apparatus in a dose-dependent manner. This inhibition can be neutralized by preincubation of antibodies with recombinant rbet1. EGTA is known to inhibit ER-Golgi transport at a stage after vesicle docking but before the actual fusion event. Antibodies against rbet1 inhibit ER-Golgi transport only when they are added before the EGTA-sensitive stage. These results suggest that rbet1 may be involved in the docking process of ER- derived vesicles with the cis-Golgi membrane.

The recycling pathway of protein ERGIC-53 and dynamics of the ER-Golgi intermediate compartment

1998 ◽  
Vol 111 (22) ◽  
pp. 3411-3425 ◽  
Author(s):  
J. Klumperman ◽  
A. Schweizer ◽  
H. Clausen ◽  
B.L. Tang ◽  
W. Hong ◽  
...  
Keyword(s):  
Golgi Apparatus ◽  
Secretory Pathway ◽  
Immunofluorescence Microscopy ◽  
Gradient Centrifugation ◽  
Membrane System ◽  
Cell Periphery ◽  
Dynamic Membrane ◽  
Early Secretory Pathway ◽  
Intermediate Compartment ◽  
Recycling Pathway

To establish recycling routes in the early secretory pathway we have studied the recycling of the ER-Golgi intermediate compartment (ERGIC) marker ERGIC-53 in HepG2 cells. Immunofluorescence microscopy showed progressive concentration of ERGIC-53 in the Golgi area at 15 degreesC. Upon rewarming to 37 degreesC ERGIC-53 redistributed into the cell periphery often via tubular processes that largely excluded anterograde transported albumin. Immunogold labeling of cells cultured at 37 degreesC revealed ERGIC-53 predominantly in characteristic beta-COP-positive tubulo-vesicular clusters both near the Golgi apparatus and in the cell periphery. Concentration of ERGIC-53 at 15 degreesC resulted from both accumulation of ERGIC-53 in the ERGIC and movement of ERGIC membranes closer to the Golgi apparatus. Upon rewarming to 37 degreesC the labeling of ERGIC-53 in the ERGIC rapidly returned to normal levels whereas ERGIC-53's labeling in the cis-Golgi was unchanged. Temperature manipulations had no effect on the average number of ERGIC-53 clusters. Density gradient centrifugation indicated that the surplus ERGIC-53 accumulating in the ERGIC at 15 degreesC was rapidly transported to the ER upon rewarming. These results suggest that the ERGIC is a dynamic membrane system composed of a constant average number of clusters and that the major recycling pathway of ERGIC-53 bypasses the Golgi apparatus.

Dictyosome tubules, a conspicuous membraneous system of the plant cell

1990 ◽  
Vol 48 (3) ◽  
pp. 702-703
Author(s):  
H.H. Mollenhauer ◽  
D.J. Morré
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Plant Cell ◽  
Membrane System ◽  
Coated Vesicle ◽  
Secretory Vesicles ◽  
Conspicuous Feature ◽  
Constant Diameter

Tubules of about 30 run diameter are a conspicuous feature of most, if not all, Golgi apparatus cisternae (Fig. 1). The tubules may be configured as fenestrae, networks, or single outward projections around the edges of the cisternae. Coated, vesicle-like membrane buds are a common feature of tubules. Short lengths of tubules connect secretory vesicles to cisternae.The function of the tubules is not known although they interconnect cisternae of closely spaced dictyosome stacks and have been postulated to be intermediates between endoplasmic reticulum and Golgi apparatus. Additionally, they may play a part, as yet undefined, in the movement of products between cisternae.This report demonstrates that the peripheral tubules of the Golgi apparatus are a conspicuous membrane system of the cell, equal to, and often exceeding, that of the flattened parts of the Golgi apparatus cisternae.Tubules were considered as cylinders of constant diameter with total lengths equal to the sum of all tubule segments.

scholarly journals The mammalian homolog of yeast Sec13p is enriched in the intermediate compartment and is essential for protein transport from the endoplasmic reticulum to the Golgi apparatus.

1997 ◽  
Vol 17 (1) ◽  
pp. 256-266 ◽  
Author(s):  
B L Tang ◽  
F Peter ◽  
J Krijnse-Locker ◽  
S H Low ◽  
G Griffiths ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Intact Cell ◽  
Predicted Amino Acid Sequence ◽  
Restrictive Temperature ◽  
Dependent Manner ◽  
Yeast Saccharomyces Cerevisiae ◽  
Golgi Transport ◽  
Intermediate Compartment

The role of COPII components in endoplasmic reticulum (ER)-Golgi transport, first identified in the yeast Saccharomyces cerevisiae, has yet to be fully characterized in higher eukaryotes. A human cDNA whose predicted amino acid sequence showed 70% similarity to the yeast Sec13p has previously been cloned. Antibodies raised against the human SEC13 protein (mSEC13) recognized a cellular protein of 35 kDa in both the soluble and membrane fractions. Like the yeast Sec13p, mSEC13 exist in the cytosol in both monomeric and higher-molecular-weight forms. Immunofluorescence microscopy localized mSEC13 to the characteristic spotty ER-Golgi intermediate compartment (ERGIC) in cells of all species examined, where it colocalized well with the KDEL receptor, an ERGIC marker, at 15 degrees C. Immunoelectron microscopy also localized mSEC13 to membrane structures close to the Golgi apparatus. mSEC13 is essential for ER-to-Golgi transport, since both the His6-tagged mSEC13 recombinant protein and the affinity-purified mSEC13 antibody inhibited the transport of restrictive temperature-arrested vesicular stomatitis virus G protein from the ER to the Golgi apparatus in a semi-intact cell assay. Moreover, cytosol immunodepleted of mSEC13 could no longer support ER-Golgi transport. Transport could be restored in a dose-dependent manner by a cytosol fraction enriched in the high-molecular-weight mSEC13 complex but not by a fraction enriched in either monomeric mSEC13 or recombinant mSEC13. As a putative component of the mammalian COPII complex, mSEC13 showed partially overlapping but mostly different properties in terms of localization, membrane recruitment, and dynamics compared to that of beta-COP, a component of the COPI complex.

Complex envelope system. Membrane systems of plant cells

1974 ◽  
Vol 268 (891) ◽  
pp. 119-128 ◽  
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Smooth Endoplasmic Reticulum ◽  
Plant Cells ◽  
Membrane System ◽  
Cellulose Microfibrils ◽  
Membrane Systems ◽  
Complex Envelope ◽  
Pectic Substances ◽  
The Matrix

The membrane system is made up of the nuclear envelopes, rough and smooth endoplasmic reticulum, Golgi apparatus and plasmalemma. Interconnexions between the various parts of the system are shown and these probably represent a flow of membrane from the endoplasmic reticulum through the Golgi apparatus to the plasmalemma. Membrane fractions have been isolated from broken cells and their function in the synthesis of polysaccharides established. It has been shown that the matrix polysaccharides of the wall (pectic substances and hemicelluloses) are formed within the membranes and that the pattern of synthesis of these polymers changes during differentiation of the cells. Cellulose microfibrils are probably synthesized at the plasmalemma which is formed by incorporation of membrane bounded vesicles from the Golgi apparatus. Thus the assembly of the polymers takes place either when the membrane is within the cytoplasm or when it is incorporated as the plasmalemma of the cell.

scholarly journals Trafficking Unconventionally via UPS

Cells ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 2009
Author(s):  
Bor Luen Tang
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Membrane Proteins ◽  
Golgi Apparatus ◽  
Protein Secretion ◽  
Vesicular Trafficking ◽  
Eukaryotic Cells

Conventional protein secretion in eukaryotic cells occurs via vesicular trafficking of proteins that are first targeted to the endoplasmic reticulum (ER), through the Golgi apparatus, and subsequently routed to the plasma membrane (PM), where membrane proteins take up residence while luminal proteins are released extracellularly [...]

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