How are the proteins produced in the endoplasmic reticulum transported to the Golgi apparatus?
|
 Show
The Golgi apparatus is an evolutionarily conserved organelle of the eukaryotic secretory pathway and plays a crucial role in decoding the positional information encoded in the genome. From: Encyclopedia of Cell Biology, 2016 Susan Standring MBE, PhD, DSc, FKC, Hon FAS, Hon FRCS, in Gray's Anatomy, 2021 The Golgi apparatus is a distinct cytomembrane system located near the nucleus and the centrosome. It
is particularly prominent in secretory cells and can be visualized when stained with silver or other metallic salts. Traffic between the endoplasmic reticulum and the Golgi apparatus is bidirectional and takes place via carrier vesicles derived from the donor site that bud, tether and fuse with the target site. Carrier vesicles in transit from the endoplasmic reticulum to the Golgi apparatus (anterograde transport) are coated by coat protein complex II (COPII), whereas COPI-containing vesicles
function in the retrograde transport route from the Golgi apparatus (reviewed inSpang (2013)). Golgins are long coiled-coil proteins attached to the cytoplasmic surface of cisternal membranes, forming a fibrillar matrix surrounding the Golgi apparatus to stabilize it; they have a role in vesicle trafficking (Witkos and Lowe 2015). The Golgi apparatus has several functions: it links anterograde and retrograde protein and
lipid flow in the secretory pathway; it is the site where protein and lipid glycosylation occurs; and it provides membrane platforms to which signalling and sorting proteins bind. Ultrastructurally, the Golgi apparatus (Fig. 1.6A) displays a continuous ribbon-like structure consisting of a stack of several flattened membranous cisternae, together with clusters of vesicles surrounding its surfaces. Cisternae differ in their
enzymatic content and activity. Small transport vesicles from the rough endoplasmic reticulum are received at one face of the Golgi stack, the convexcis-face (entry or forming surface). Here, they deliver their contents to the first cisterna in the series by membrane fusion. The protein is transported from the edges of this cisterna to the next cisterna by vesicular budding and then fusion, and this process is repeated across medial cisternae until the final cisterna at the
concavetrans-face (exit or condensing surface) is reached. Here, larger vesicles are formed for delivery to other parts of the cell. Thecis-Golgi andtrans-Golgi membranous networks form an integral part of the Golgi apparatus (Fig. 1.6B). Thecis-Golgi network is a region of complex membranous channels interposed between the rough endoplasmic reticulum and the Golgicis-face, which
receives and transmits vesicles in both directions. Its function is to select appropriate proteins synthesized on the rough endoplasmic reticulum for delivery by vesicles to the Golgi stack, while inappropriate proteins are shuttled back to the rough endoplasmic reticulum. Thetrans-Golgi network, at the other side of the Golgi stack, is also a region of interconnected membrane channels engaged in protein sorting. Here, modified proteins
processed in the Golgi cisternae are packaged selectively into vesicles and dispatched to different parts of the cell. The packaging depends on the detection, by thetrans-Golgi network, of particular amino acid signal sequences, leading to their enclosure in membranes of appropriate composition that will further modify their contents, e.g. by extracting water to concentrate them (vesicles entering the exocytosis pathway) or by pumping in protons to acidify their contents (lysosomes
destined for the intracellular sorting pathway). The membranes contain specific signal proteins that may allocate them to microtubule-based transport pathways and allow them to dock with appropriate targets elsewhere in the cell, e.g. the plasma membrane in the case of secretory vesicles. Vesicle formation and budding at thetrans-Golgi network involves the addition of clathrin on their external surface, to form coated pits. OrganellesM.W. Gray, in Brenner's Encyclopedia of Genetics (Second Edition), 2013 Golgi bodyThe Golgi body (also called Golgi apparatus or Golgi complex) consists of a series of disk-like membranes (cisternae) organized into stacks, or dictyosomes. Newly synthesized glycoproteins are transported from the ER lumen to the Golgi body for further addition of sugar residues to the oligosaccharide core. These carbohydrate tags serve as signals for sorting and targeting of the mature glycoproteins to their appropriate compartments within the cell, or out of the cell. The Golgi body has a distinct polarity, with proteins entering its cis (or entry) face via transport vesicles called transitional elements that bud from the ER, and exiting through its trans face via secretory vesicles. These vesicles will fuse with the plasma membrane to disgorge the new proteins outside the cell (i.e., ‘secrete’), or to insert the proteins into the plasma membrane. Read full chapter URL: https://www.sciencedirect.com/science/article/pii/B9780123749840010974 Proprioception in Hand RehabilitationTerri M. Skirven OTR/L, CHT, in Rehabilitation of the Hand and Upper Extremity, 2021 Golgi-like EndingsThe Golgi-like endings, type III, are named after the Italian anatomist and Nobel laureate for physiology or medicine (1906) Camillo Golgi,31 who initially discovered this sensory nerve endings as the “Golgi tendon organ” in the myotendinous junction in 1878. To express that ligaments are not containing the Golgi tendon organ of the myotendinous junction, these ligamentous receptors are described as “Golgi-like endings.”23,32 They are the largest sensory end organs in the ligamentous tissue. They consist of a thin fusiform capsule enclosing many tightly branching terminal nerve filaments of a large axon (seeFig. 99.2C). These slowly adapting mechanoreceptors respond to extreme joint movement.23 General Characteristics of the Euprotista (Protozoa)Burton J. Bogitsh, ... Thomas N. Oeltmann, in Human Parasitology (Fifth Edition), 2019 Golgi ComplexThe Golgi complex is a cytoplasmic organelle whose specific function in protozoans is essentially identical to that in other eukaryotes. The Golgi is the seat of glycosylation of a number of secretory products of the cell. It is in the cisternae of the Golgi complex, for instance, that the final carbohydrate moieties are added to the glycocalyx associated with the plasma membrane. The arrangement and number of Golgi complexes vary during the life cycle of many protozoans. Thus, cyst-forming protistans may lose their Golgi complexes during encystation, only to resynthesize them when they excyst. The so-called parabasal body of protozoans is homologous to the Golgi complex of other eukaryotic cells but with several morphological differences, the most notable of which is the frequent presence of a fibril, the parabasal filament, running from the cisternae of the Golgi complex to one or more basal bodies. Read full chapter URL: https://www.sciencedirect.com/science/article/pii/B9780128137123000035 Liver Physiology and Energy MetabolismMark Feldman MD, in Sleisenger and Fordtran's Gastrointestinal and Liver Disease, 2021 Golgi ComplexThe Golgi complex consists of a stack of flat sac-like membranes (cisternae) that are dilated at the margins.23 Many proteins synthesized in the rough ER are transported to the Golgi apparatus in protein-filled transition vesicles. The aspect of the Golgi complex facing the ER is the cis face; the opposite side is termed the trans face. Glycoproteins are thought to be transported between the Golgi sacs via shuttle vesicles. The highly mannosylated glycosyl moiety of proteins that areN-glycosylated in the ER are processed in the Golgi sacs into mature forms. Some other proteins areO-glycosylated in the Golgi complex. These proteins are then sorted for transport to appropriate cellular organelles (see later discussion of exocytosis and endocytosis).24 Mechanisms and Morphology of Cellular Injury, Adaptation, and Death2Margaret A. Miller, James F. Zachary, in Pathologic Basis of Veterinary Disease (Sixth Edition), 2017 Golgi ComplexThe Golgi complex, also commonly called the Golgi apparatus, is a series of flattened membrane-bound sacs with its inner face (cis or entry face) near the rER in a paranuclear position (see Fig. 1-3). Proteins made in the rER are delivered to the entry face of the Golgi complex by transport vesicles. As the proteins traverse the Golgi complex, they are processed (e.g., carbohydrate moieties added through glycosylation) and packaged into secretory vesicles to be released from the outer (trans) face of the Golgi complex into the cytosol, either for use by the cell that produced them, as in the case of lysosomal enzymes, or (more commonly) for delivery to the plasma membrane for export. Transmission electron microscopy is usually required to visualize the Golgi complex. However, an active Golgi complex, such as that needed for processing and packaging of immunoglobulin molecules, is large enough to impart a paranuclear eosinophilic pallor to plasma cells in a hematoxylin and eosin (H&E)–stained histologic section. Read full chapter URL: https://www.sciencedirect.com/science/article/pii/B9780323357753000011 Platelet StructureJames G. White, in Platelets (Third Edition), 2013 1 Golgi ComplexesGolgi complexes consisting of parallel-associated, flattened sacules are prominent in the perinuclear cytoplasm of the megakaryocyte during granulopoiesis. When organelle formation is completed, the extensively developed, highly complex Golgi zones move to the periphery of the megakaryocyte cytoplasm and almost completely disappear before proplatelets develop. Only residual elements consisting of a few parallel-associated, flattened sacules with no budding vesicles are found in less than 1% of circulating platelets (Fig. 7-62). Its mission was accomplished before the circulating platelet was born. But not always. Platelets from patients with some of the hypogranular platelet syndromes carry significant numbers of Golgi complexes to the peripheral blood.75 This is particularly true for WPS.56 Patients with this disorder have mild thrombocytopenia, increased mean platelet volume, decreased sensitivity to aggregating agents, and prolonged bleeding times. Four to thirteen percent of their platelets contain large, fully developed Golgi complexes actively budding smooth and coated vesicles and frequently associated with centrioles (Figs. 7-63 and 7-64). As many as seven Golgi complexes and five centrioles have been observed in single platelets. The findings indicate that platelets from patients with some hypogranular platelet disorders are continuing the process of granulopoiesis into circulating platelets. Recognition that this phenomenon can occur and is characteristic of WPS will prevent the patients from being diagnosed incorrectly to have a leukemic disorder. Figure 7-63. Platelet from a patient with the White platelet syndrome. There are five well-developed Golgi complexes (↑) shedding numerous smooth and coated vesicles in the cytoplasm. Mitochondria (M) are more numerous than α granules (G). Mag.×22,000. Figure 7-64. White platelet syndrome platelet containing a large Golgi complex (Gc) and four centrioles (↑). Mag.×22,000. Read full chapter URL: https://www.sciencedirect.com/science/article/pii/B9780123878373000079 Golgi Complex and Endosome AntibodiesMarvin J. Fritzler, Edward K.L. Chan, in Autoantibodies (Third Edition), 2014 Disease associationDisease prevalenceAGA was first identified in the serum of a Sjögren syndrome (SjS) patient with lymphoma. This was followed by other reports that described AGAs in SjS, systemic lupus erythematosus (SLE), rheumatoid arthritis, mixed connective tissue disease, Wegener granulomatosis, and human immunodeficiency virus (HIV) infection (Table 32.2 and reviewed in [8]). Immunoblotting and immunoprecipitation studies have shown that the proteins recognized by human AGA are remarkably heterogeneous [3]. Although AGAs are generally considered to be rare, at Mitogen Advanced Diagnostics Laboratory at the University of Calgary they are seen at least as common as antibodies to Sm. In a study of 80 sera, the frequency of AGA directed to specific Golgi components was correlated with the molecular masses of the golgins [3]. Thus, autoantibodies to giantin/macrogolgin, the highest molecular weight golgin, were the most frequent, being found in 50% of the AGA sera. By contrast, antibodies to golgin 97 were the least common, being found in only approximately 4% of the AGA sera. The most reactive of the giantin/macrogolgin epitopes were those that included the C-terminal transmembrane domain [3]. There is emerging consensus that AGA are not disease specific [4,17], although high titers of AGA have been suggested to constitute an early sign of systemic autoimmune diseases even in the absence of clear clinical manifestations [18]. Table 32.2. Diseases Associated with Anti-Golgi and Anti-endosome Antibodies
BHMT1: betaine homocysteine methyl transferase 1; CLIP-170: cytoplasmic linker protein-170; EEA1: early endosome antigen 1; GRASP-1: glutamate receptor interacting protein-associated protein-1; LBPA: lysobisphosphatidic acid. Autoantibodies to EEA1 have been associated with neurologic diseases and a variety of systemic and organ-specific autoimmune diseases (Table 32.2 and reviewed in [8,14]). Further study of the sera that reacted with EEA1 showed that 94% reacted with the partial length EEA1 constructs that included the C-terminal zinc finger (+FYVE) and the methyl accepting domain (amino acids 82–1411) in an addressable laser bead assay [14]. A study of the epitopes bound by sera from patients with neurologic diseases and patients with other conditions suggested that the later sera from patients recognized epitopes in the central and C-terminal EEA1 domains, whereas the patients with neurologic disease recognized a more restricted set of epitopes in the C-terminal domain [14]. The prevalence of AGA and anti-endosome antibodies in cohorts of SjS, SLE, and systemic sclerosis, as detected by screening IIF assays, suggest that the prevalence of these autoantibodies in those conditions is less than 1%. Diagnostic valueFurther studies of multi-institutional serologic cohorts are required to determine the specificity and sensitivity of antibodies to the Golgi complex and endosome autoantigens. Prognostic valueLongitudinal studies of patients with AGA or anti-endosome antibodies have not been reported. Disease activityThere are no studies of the relationship of these autoantibodies to disease activity. Organ involvement/damageTo date there are no studies of organ involvement or damage that can be directly attributed to AGA or endosome autoantibodies. Read full chapter URL: https://www.sciencedirect.com/science/article/pii/B9780444563781000320 The Cell: Basic Structure and FunctionMagnus von Knebel Doeberitz, Nicolas Wentzensen, in Comprehensive Cytopathology (Third Edition), 2008 Golgi ApparatusThe Golgi apparatus is part of the membrane system that also contains the ER. It consists of stacked membrane-coated cavities, called dictyosomes (Fig. 1.4B). The Golgi apparatus is located close to the nucleus and can be very large in secretory cells, where it fills almost the complete cytoplasm. The convex side facing the ER/nucleus is called cis-Golgi; the concave side facing the cytoplasm is called trans-Golgi. From the Golgi apparatus, small vesicles transport products to other cellular sites or the exterior. Inside the structure, complex biochemical operations are being performed most of them resulting in post-translational modifications of synthesized proteins. Several secretory mammalian cell types are characterized by a prominent polarized Golgi apparatus located between the nucleus and the luminal surface: Goblet cells in the respiratory and digestive tract produce large amounts of glycoproteins, pancreatic cells secrete enzymes such as zymogen, and breast cells produce milk droplets. Read full chapter URL: https://www.sciencedirect.com/science/article/pii/B9781416042082100016 Liver Physiology and Energy MetabolismNamita Roy-Chowdhury, Jayanta Roy-Chowdhury, in Sleisenger and Fordtran's Gastrointestinal and Liver Disease (Ninth Edition), 2010 Golgi ComplexThe Golgi complex consists of a stack of flat sac-like membranes (cysternae) that are dilated at the margins.21 Many proteins synthesized in the rough ER are transported to the Golgi apparatus in protein-filled transition vesicles. The aspect of the Golgi complex facing the ER is the cis face; the opposite side is termed the trans face. Glycoproteins are thought to be transported between the Golgi sacs via shuttle vesicles. The highly mannosylated glycosyl moiety of proteins that are N-glycosylated in the ER are processed in the Golgi sacs into mature forms. Some other proteins are O-glycosylated in the Golgi complex. These proteins are then sorted for transport to appropriate cellular organelles (see later discussion of exocytosis and endocytosis).22 Read full chapter URL: https://www.sciencedirect.com/science/article/pii/B978141606189200072X How are proteins transported from ER to Golgi?COPII-coated vesicles transport cargo proteins from the ER to the Golgi; COPI-coated vesicles transport cargo in the retrograde direction (from the cis-Golgi back to the ER) and between Golgi cisternae; and clathrin-coated vesicles form from the plasma membrane and the TGN to fuse with endosomes or lysosomes (Fig. 1).
How are proteins transported out of the endoplasmic reticulum?From the endoplasmic reticulum, proteins are transported in vesicles to the Golgi apparatus, where they are further processed and sorted for transport to lysosomes, the plasma membrane, or secretion from the cell.
How do proteins arrive at the Golgi apparatus and what happens to them there?Protein cargo moves from the ER to the Golgi, is modified within the Golgi, and is then sent to various destinations in the cell, including the lysosomes and the cell surface. The Golgi processes proteins made by the endoplasmic reticulum (ER) before sending them out to the cell.
How do the endoplasmic reticulum and Golgi apparatus work together?The Golgi apparatus receives proteins and lipids (fats) from the rough endoplasmic reticulum. It modifies some of them and sorts, concentrates and packs them into sealed droplets called vesicles.
|
