scholarly journals Assembly and disassembly of the Golgi complex: two processes arranged in a cis-trans direction.

1992 ◽  
Vol 116 (1) ◽  
pp. 69-83 ◽  
Author(s):  
J Alcalde ◽  
P Bonay ◽  
A Roa ◽  
S Vilaro ◽  
I V Sandoval
Keyword(s):  
Membrane Proteins ◽  
Golgi Complex ◽  
Rat Kidney ◽  
Brefeldin A ◽  
Golgi Membrane ◽  
Temperature Conditions ◽  
Selective Fusion ◽  
Normal Rat ◽  
Short Times

We have studied the disassembly and assembly of two morphologically and functionally distinct parts of the Golgi complex, the cis/middle and trans cisterna/trans network compartments. For this purpose we have followed the redistribution of three cis/middle- (GMPc-1, GMPc-2, MG 160) and two trans- (GMPt-1 and GMPt-2) Golgi membrane proteins during and after treatment of normal rat kidney (NRK) cells with brefeldin A (BFA). BFA induced complete disassembly of the cis/middle- and trans-Golgi complex and translocation of GMPc and GMPt to the ER. Cells treated for short times (3 min) with BFA showed extensive disorganization of both cis/middle- and trans-Golgi complexes. However, complete disorganization of the trans part required much longer incubations with the drug. Upon removal of BFA the Golgi complex was reassembled by a process consisting of three steps: (a) exist of cis/middle proteins from the ER and their accumulation into vesicular structures scattered throughout the cytoplasm; (b) gradual relocation and accumulation of the trans proteins in the vesicles containing the cis/middle proteins; and (c) assembly of the cisternae, and reconstruction of the Golgi complex within an area located in the vicinity of the centrosome from which the ER was excluded. Reconstruction of the cis/middle-Golgi complex occurred under temperature conditions inhibitory of the reorganization of the trans-Golgi complex, and was dependent on microtubules. Reconstruction of the trans-Golgi complex, disrupted with nocodazole after selective fusion of the cis/middle-Golgi complex with the ER, occurred after the release of cis/middle-Golgi proteins from the ER and the assembly of the cis/middle cisternae.

scholarly journals Golgi Structure in Three Dimensions: Functional Insights from the Normal Rat Kidney Cell

1999 ◽  
Vol 144 (6) ◽  
pp. 1135-1149 ◽  
Author(s):  
Mark S. Ladinsky ◽  
David N. Mastronarde ◽  
J. Richard McIntosh ◽  
Kathryn E. Howell ◽  
L. Andrew Staehelin
Keyword(s):  
Golgi Complex ◽  
Rat Kidney ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Structural Constraints ◽  
Vesicular Traffic ◽  
Golgi Region ◽  
Normal Rat ◽  
Em Tomography ◽  
Cis And Trans

Three-dimensional reconstructions of portions of the Golgi complex from cryofixed, freeze-substituted normal rat kidney cells have been made by dual-axis, high-voltage EM tomography at ∼7-nm resolution. The reconstruction shown here (∼1 × 1 × 4 μm3) contains two stacks of seven cisternae separated by a noncompact region across which bridges connect some cisternae at equivalent levels, but none at nonequivalent levels. The rest of the noncompact region is filled with both vesicles and polymorphic membranous elements. All cisternae are fenestrated and display coated buds. They all have about the same surface area, but they differ in volume by as much as 50%. The trans-most cisterna produces exclusively clathrin-coated buds, whereas the others display only nonclathrin coated buds. This finding challenges traditional views of where sorting occurs within the Golgi complex. Tubules with budding profiles extend from the margins of both cis and trans cisternae. They pass beyond neighboring cisternae, suggesting that these tubules contribute to traffic to and/or from the Golgi. Vesicle-filled “wells” open to both the cis and lateral sides of the stacks. The stacks of cisternae are positioned between two types of ER, cis and trans. The cis ER lies adjacent to the ER-Golgi intermediate compartment, which consists of discrete polymorphic membranous elements layered in front of the cis-most Golgi cisterna. The extensive trans ER forms close contacts with the two trans-most cisternae; this apposition may permit direct transfer of lipids between ER and Golgi membranes. Within 0.2 μm of the cisternae studied, there are 394 vesicles (8 clathrin coated, 190 nonclathrin coated, and 196 noncoated), indicating considerable vesicular traffic in this Golgi region. Our data place structural constraints on models of trafficking to, through, and from the Golgi complex.

scholarly journals TGN38/41 recycles between the cell surface and the TGN: brefeldin A affects its rate of return to the TGN.

1993 ◽  
Vol 4 (1) ◽  
pp. 93-105 ◽  
Author(s):  
B Reaves ◽  
M Horn ◽  
G Banting
Keyword(s):  
Plasma Membrane ◽  
Specific Binding ◽  
Rat Kidney ◽  
Brefeldin A ◽  
Integral Membrane Protein ◽  
Intracellular Compartments ◽  
Normal Rat ◽  
Golgi Network ◽  
Lumenal Domain ◽  
Kinetics Of

TGN38 and TGN41 are isoforms of an integral membrane protein (TGN38/41) that is predominantly localized to the trans-Golgi network (TGN) of normal rat kidney cells. Polyclonal antisera to TGN38/41 have been used to monitor its appearance at, and removal from, the surface of control and Brefeldin A (BFA)-treated cells. Antibodies that recognize the lumenal domain of TGN38/41 are capable of specific binding to the surface of both control and BFA-treated cells. In both control and BFA-treated cells internalized TGN38/41 is targeted to the TGN; however, there are differences in 1) the morphology of the intracellular structures through which TGN38/41 passes and 2) the kinetics of internalization. These data demonstrate that TGN38/41 cycles between the plasma membrane and the TGN in control and BFA-treated cells and suggest that recycling pathways between the plasma membrane and the TGN exist for predominantly TGN proteins as well as those that normally cycle to other intracellular compartments. They also demonstrate that addition of BFA not only alters the morphology and localization of the TGN but also the kinetics of endocytosis.

Direct targeting of cis-Golgi matrix proteins to the Golgi apparatus

2001 ◽  
Vol 114 (22) ◽  
pp. 4105-4115
Author(s):  
Shin-ichiro Yoshimura ◽  
Nobuhiro Nakamura ◽  
Francis A. Barr ◽  
Yoshio Misumi ◽  
Yukio Ikehara ◽  
...  
Keyword(s):  
Golgi Apparatus ◽  
Rat Kidney ◽  
Subcellular Fractionation ◽  
Golgi Membrane ◽  
Microsomal Membranes ◽  
Normal Rat ◽  
Direct Targeting ◽  
Golgi Matrix ◽  
Er Membrane

The targeting route of newly synthesized GM130 and GRASP65 to the Golgi apparatus was investigated by three different approaches. First, localization of pulse labeled GM130 and GRASP65 in normal rat kidney (NRK) cells was traced by subcellular fractionation followed by immunoprecipitation. Immediately after the pulse labeling, GM130 and GRASP65 were found in the Golgi but not in the endoplasmic reticulum (ER) membrane fractions, whereas a control Golgi membrane protein was still found in the ER membrane fractions. Second, epitope tagged GM130 and GRASP65 were expressed in NRK cells by plasmid microinjection into the nuclei and their localization was analyzed by immunofluorescence. When ER to Golgi transport was inhibited by prior microinjection of a GTP-restricted mutant of Sar1 protein into the cytosol, the expressed GM130 and GRASP65 showed clear Golgi localization. Last, binding of GM130 and GRASP65 to the membranes was analyzed in vitro. In vitro synthesized GM130 and GRASP65 specifically bound to purified Golgi membranes but not to microsomal membranes. The bound GM130 and GRASP65 were found to form a complex with pre-existing counterparts on the Golgi membrane. These results strongly suggested that GM130 and GRASP65 are directly targeted to the Golgi membrane without initial assembly on the ER and subsequent vesicular transport to the Golgi apparatus.

scholarly journals Regulation of Golgi turnover by CALCOCO1-mediated selective autophagy

2021 ◽  
Vol 220 (6) ◽  
Author(s):  
Thaddaeus Mutugi Nthiga ◽  
Birendra Kumar Shrestha ◽  
Jack-Ansgar Bruun ◽  
Kenneth Bowitz Larsen ◽  
Trond Lamark ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Golgi Complex ◽  
Eukaryotic Cells ◽  
Golgi Membrane ◽  
Selective Autophagy ◽  
Physiological Demands ◽  
Size And Morphology ◽  
In Cells

The Golgi complex is essential for the processing, sorting, and trafficking of newly synthesized proteins and lipids. Golgi turnover is regulated to meet different cellular physiological demands. The role of autophagy in the turnover of Golgi, however, has not been clarified. Here we show that CALCOCO1 binds the Golgi-resident palmitoyltransferase ZDHHC17 to facilitate Golgi degradation by autophagy during starvation. Depletion of CALCOCO1 in cells causes expansion of the Golgi and accumulation of its structural and membrane proteins. ZDHHC17 itself is degraded by autophagy together with other Golgi membrane proteins such as TMEM165. Taken together, our data suggest a model in which CALCOCO1 mediates selective Golgiphagy to control Golgi size and morphology in eukaryotic cells via its interaction with ZDHHC17.

scholarly journals Cholesterol-independent Targeting of Golgi Membrane Proteins in Insect Cells

1997 ◽  
Vol 8 (11) ◽  
pp. 2111-2118 ◽  
Author(s):  
Melissa M. Rolls ◽  
Marianne T. Marquardt ◽  
Margaret Kielian ◽  
Carolyn E. Machamer
Keyword(s):  
Membrane Proteins ◽  
Golgi Complex ◽  
Secretory Pathway ◽  
Protein Targeting ◽  
Insect Cells ◽  
Golgi Membrane ◽  
Cellular Cholesterol ◽  
Golgi Region ◽  
Intracellular Organelles ◽  
Aedes Albopictus Cells

Distinct lipid compositions of intracellular organelles could provide a physical basis for targeting of membrane proteins, particularly where transmembrane domains have been shown to play a role. We tested the possibility that cholesterol is required for targeting of membrane proteins to the Golgi complex. We used insect cells for our studies because they are cholesterol auxotrophs and can be depleted of cholesterol by growth in delipidated serum. We found that two well-characterized mammalian Golgi proteins were targeted to the Golgi region of Aedes albopictus cells, both in the presence and absence of cellular cholesterol. Our results imply that a cholesterol gradient through the secretory pathway is not required for membrane protein targeting to the Golgi complex, at least in insect cells.

Golgi membrane skeleton: identification, localization and oligomerization of a 195 kDa ankyrin isoform associated with the Golgi complex

1997 ◽  
Vol 110 (10) ◽  
pp. 1239-1249 ◽  
Author(s):  
K.A. Beck ◽  
J.A. Buchanan ◽  
W.J. Nelson
Keyword(s):  
Golgi Complex ◽  
Cultured Cells ◽  
Mdck Cells ◽  
Affinity Purification ◽  
Light And Electron Microscopy ◽  
Brefeldin A ◽  
Membrane Skeleton ◽  
Coat Proteins ◽  
Golgi Membrane ◽  
Triton X

To extend our finding of a Golgi-localized form of the membrane skeleton protein spectrin, we have identified an isoform of ankyrin that associates at steady state with the Golgi complex. Immuno-light and -electron microscopy show that this ankyrin isoform localizes to the perinuclear cytoplasm on tubular vesicular structures that co-stain with Golgi marker proteins. An antiserum raised against erythrocyte ankyrin, which was used to identify the Golgi ankyrin, recognized three prominent polypeptides of 220, 213 and 195 kDa in MDCK cells. Affinity purification of this antiserum against each of these MDCK cell ankyrins revealed that only an antibody specific for the 195 kDa form retained the ability to stain the Golgi complex; affinity purified antibody preparations specific for both the 220 and 213 kDa forms stained punctate and reticular cytoplasmic structures distinct from the Golgi complex. Antibody specific for the 195 kDa ankyrin did not recognize a recently identified 119 kDa ankyrin that is also localized to the Golgi. The 195 kDa Golgi ankyrin binds purified erythrocyte spectrin, and rapidly co-sediments with Golgi beta-spectrin during brief, low speed centrifugation of Triton X-100 extracts of MDCK cells. Golgi ankyrin and beta-spectrin are retained on tubular vesicular ‘Golgi ghosts’ following extraction of cultured cells with Triton X-100. Significantly, Golgi ghost tubules containing ankyrin/spectrin are co-linear with individual microtubules, suggesting a role for both Golgi membrane skeleton and microtubules in spatial localization of the Golgi. Golgi ankyrin dissociates from Golgi membranes during mitosis and in cells treated with brefeldin A, indicating that Golgi ankyrin has a dynamic assembly state similar to that of Golgi spectrin and other Golgi membrane coat proteins.

scholarly journals Sec6/8 complexes on trans-Golgi network and plasma membrane regulate late stages of exocytosis in mammalian cells

2001 ◽  
Vol 155 (4) ◽  
pp. 593-604 ◽  
Author(s):  
Charles Yeaman ◽  
Kent K. Grindstaff ◽  
Jessica R. Wright ◽  
W. James Nelson
Keyword(s):  
Plasma Membrane ◽  
Mammalian Cells ◽  
Rat Kidney ◽  
Brefeldin A ◽  
Intercellular Junctions ◽  
Trans Golgi Network ◽  
Cargo Protein ◽  
Normal Rat ◽  
Golgi Network ◽  
Exocytic Pathway

Sec6/8 complex regulates delivery of exocytic vesicles to plasma membrane docking sites, but how it is recruited to specific sites in the exocytic pathway is poorly understood. We identified an Sec6/8 complex on trans-Golgi network (TGN) and plasma membrane in normal rat kidney (NRK) cells that formed either fibroblast- (NRK-49F) or epithelial-like (NRK-52E) intercellular junctions. At both TGN and plasma membrane, Sec6/8 complex colocalizes with exocytic cargo protein, vesicular stomatitis virus G protein (VSVG)-tsO45. Newly synthesized Sec6/8 complex is simultaneously recruited from the cytosol to both sites. However, brefeldin A treatment inhibits recruitment to the plasma membrane and other treatments that block exocytosis (e.g., expression of kinase-inactive protein kinase D and low temperature incubation) cause accumulation of Sec6/8 on the TGN, indicating that steady-state distribution of Sec6/8 complex depends on continuous exocytic vesicle trafficking. Addition of antibodies specific for TGN- or plasma membrane–bound Sec6/8 complexes to semiintact NRK cells results in cargo accumulation in a perinuclear region or near the plasma membrane, respectively. These results indicate that Sec6/8 complex is required for several steps in exocytic transport of vesicles between TGN and plasma membrane.

A group of integral membrane proteins of the rat liver Golgi contains a conserved protein of 100 kDa

1994 ◽  
Vol 107 (12) ◽  
pp. 3425-3436
Author(s):  
J.G. Pryde
Keyword(s):  
Membrane Proteins ◽  
Rat Liver ◽  
Golgi Complex ◽  
Immunofluorescence Microscopy ◽  
Mammalian Species ◽  
Polyclonal Antiserum ◽  
Integral Membrane Proteins ◽  
Golgi Membrane ◽  
Wide Range ◽  
Triton X

Rat liver Golgi membranes were washed with KCl and urea, and a polyclonal antiserum that stained the Golgi complex by immunofluorescence microscopy was raised. A group of proteins of apparent molecular mass 500 kDa, 200 kDa and 100 kDa were identified by immunoblotting with the antiserum, and were enriched in the Golgi membrane fraction. These proteins were also localised to the Golgi by immunofluorescence microscopy with affinity-purified antibodies. They are integral membrane proteins, and protease digestion experiments suggested that they are not exposed on the cytoplasmic face of the Golgi membrane. Immunofluorescence microscopy showed that staining of the Golgi complex by antibodies to the 100 kDa Golgi protein can be demonstrated among a wide range of mammalian species. This conservation may point to an important structural or functional role for the molecule. When the 100 kDa protein was reduced with dithiothreitol it was no longer recognised by the anti-Golgi antiserum. During phase separation in Triton X-114 the 100 kDa protein partitioned into the aqueous phase, rather than into the detergent phase, suggesting that it has a large luminal domain of hydrophilic amino acids.

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