Golgi complex

This organelle is also known as the Golgi or Golgi apparatus and is named after the Italian cytologist Camilo Golgi, who was one of the first to study it. 

The Golgi has distinct forms in different cell types. The most characteristic arrangement is a stack of circular flattened vesicles, with variable sizes, each one held by a single membrane in which can be found smaller spherical vesicles that bud off from the larger ones. In many cells, the Golgi complex is situated near the cell nucleus but in other cells, it is dispersed in the cytoplasm. 

The Golgi complex receives products from the endoplasmic reticulum and packs them in secretory vesicles, which are conducted and fused to the external cell membrane. In this process, termed exocytosis, the vesicle content is secreted into the outer environment. 

Once the mucin dimeric precursors reach the Golgi complex, they are O-glycosylated and N-glycosylation is completed. In vitro studies with purified, de-glycosylated gel-forming mucins (Rose et al. 1984, Shogren et al. 1989  

---

Brefeldin A, an antiviral agent which impedes protein transport from the endoplasmic reticulum to the Golgi complex, was synthesized as the racemate using a number of interesting diastereoselective reactions. 

The membrane tubules and lamellae of the endoplasmic reticulum (ER) are extended in the cell with the use of MTs and actin filaments. Kinesin motors are required for stretching out the ER, whereas depolymerization of microtubules causes the retraction of the ER to the cell centre in an actin-dependent manner. Newly synthesized proteins in the ER are moved by dynein motors along MTs to the Golgi complex (GC), where they are modified and packaged. The resulting vesicles move along the MTs to the cell periphery transported by kinesin motors. MTs determine the shape and the position also of the GC. Their depolymerization causes the fragmentation and dispersal of the GC. Dynein motors are required to rebuild the GC. 

Turner, G.R. Tartakoff, A.M. (1989). The response of the Golgi complex to microtubule alterations The roles of metabolic energy and membrane traffic in Golgi complex organization. J. Cell Biol. 109,2081-2088. 

The most common sterol in membranes is cholesterol (Chapter 14), which resides mainly in the plasma membranes of mammalian cells but can also be found in lesser quantities in mitochondria, Golgi complexes, and nuclear membranes. Cholesterol intercalates among the phospholipids of the membrane, with its hydroxyl group at the aqueous interface and the remainder of the molecule within the leaflet. Its effect on the fluidity of membranes is discussed subsequently. 

Wu CC et al. Proteomic analysis of two functional states of the Golgi complex in mammary epithelial cells. Traffic 2000 1 769-782. 

Taylor RS et al. Proteomics of rat liver Golgi complex minor proteins are identified through sequential fractionation. Electrophoresis 2000 21 3441-3459. 

Di Campli, A., Valderrama, F., Babia, T., De Matteis, M. A., Luini, A. and Egea, G. Morphological changes in the Golgi complex correlate with actin cytoskeleton rearrangements. Cell Motil. Cytoskeleton 43 334-348,1999. 

Valderrama, F., Babia, T., Ayala, I., Kok, J. W., Renau-Piqueras, J. and Egea, G. Actin microfilaments are essential for the cytological positioning and morphology of the Golgi complex. Eur.. Cell Biol. 76 9-17,1998. 

Biosynthetic and secretory cargo leaving the ER is packaged in COPII-coated vesicles for delivery to the Golgi complex 146 The Golgi apparatus is a highly polarized structure consisting of a series of flattened cisternae, usually located near the nucleus and the centrosome 146... 

Processing of proteins in the Golgi complex includes sorting and glycosylation of membrane proteins and secretory proteins 148 Proteins and lipids move through Golgi cisternae from the cis to the trans direction 148... 

Immunoelectron microscopic and biochemical fractionation data on specific processing enzymes have permitted the localization of specific processing steps in the processing pathway for proteins in the Golgi complex. The distribution of many remaining enzymes and steps has not yet been determined. The distribution for each step indicated in this table reflects a significant enrichment rather than an exclusive localization. 

Saraste, J. and Kuismanen, E. Pathways of protein sorting and membrane traffic between the rough endoplasmic reticulum and the Golgi complex. Semin. Cell Biol. 3 343-355,1992. 

Drug studies demonstrated a requirement that most proteins destined for fast axonal transport traverse the Golgi stacks, where membrane proteins are post-transla-tionally modified, sorted and packaged [9] (Fig. 28-7). This suggests that proteins in fast axonal transport must either pass through the Golgi complex or associate with... 

In neurons and non-neuronal cells, kinesin is associated with a variety of MBOs, ranging from synaptic vesicles to mitochondria to lysosomes. In addition to its role in fast axonal transport and related phenomena in non-neuronal cells, kinesin appears to be involved in constitutive cycling of membranes between the Golgi and endoplasmic reticulum. However, kinesin is not associated with all cellular membranes. For example, the nucleus, membranes of the Golgi complex and the plasma membrane all appear to lack kinesin. Kinesin interactions with membranes are thought to involve the light chains and carboxyl termini of heavy chains. However, neither this selectivity nor the molecular basis for binding of kinesin and other motors to membranes is well understood. 

Collect the supernatant and then ultracentrifuge at 200,000g for 20 min to precipitate the crude microsomal fraction that contains the ER, Golgi complex, tonoplast, and plasma membrane. 

The marker enzymes used in this experiment are as follows vanadate-sensitive H+-ATPase (plasma membrane), nitrate-sensitive H+-ATPase or pyrophosphatase (tonoplast), TritonX-100 stimulated-UDPase or IDPase (Golgi complex), antimycin A-insensitive NADPH cytochrome c reductase (ER), and cytochrome c oxidase (mitochondria inner membrane). NADH cytochrome c reductase activity is found to be 10 times higher than NADPH cytochrome c reductase activity. Chlorophyll content can be measured as the chloroplast marker. The chlorophyll content is calculated by the following equation. Before measurement, auto zero is performed at 750 ran. 

Fig. 3. Distribution ofvarious membrane markers (ER, tonoplast, Golgi complex, and mitochondrion) in the fractions of linear sucrose density gradient fractionation of mulberry cortical parenchyma cells in February.

Phosphotungstic acid (PTA) 1 g STA or PTA in 100 mL of 10% aqueous Plasma membrane Golgi complex-... 

In microorganisms, visualization of the lysosomal system of different species of malaria parasites, (19), the endoplasmic reticulum-Golgi complex system of Tritrichomonas foetus (20) and the Golgi complex and primary lysosomes of Pneumocystis carinii (30) has been attempted using ZIO staining. 

Benchimol M, De Souza W. Tritrichomonas foetus, cytochemical visualization of the endoplasmic reticulum-Golgi complex and lipids. Exper Parasitol 1985 59 51-58. 

Locke M, Huie P. The mystery of the unstained Golgi complex cistemae. J Histo-chem Cytochem 1983 31 1019-1032. 

Palluault F, Dei-Cas E, Slomianny C, Soulez B, Camus D. Golgi complex and lyso-somes in rabbit derived Pneumocystis carinii. Biol Cell 1990 70 73-82. 

---