Golgi apparatus

The Golgi complex is located in the supranuclear region (Dalen 1983). 

Mitochondria are the focus of one of the most intensive research efforts in all of biochemistry, owing to the essential metabolic processes they carry on (the citric acid cycle, fatty acid oxidation, and electron transport are but a few) and most particularly to the nature of the process of oxidative phosphorylation. Table 3 lists the major metabolic pathways and processes that occur within the confines of the mitochondrion. A complete list of enzymes associated with mitochondria is available (Altman and Katz, 1976), as is a review on methods of preparation (Sottocasa, 1976). 

Citric acid cycle Branched-chain amino acid metabolism 

Ketone-body metabolism Electron-transport chain and p ho s phate - transfe r enzymes 

Several enzymes of heme biosynthesis Part of urea cycle 

The inner membrane of the mitochondrion accounts for 80-95% of the protein found in mitochondrial membranes and over 90% of the lipid. It is the site of the respiratory chain and the synthesis of ATP. It is this membrane, in conjunction with studies on transport through the plasma membrane, that has contributed most forcefully both to the viewpoint of the anisotropic organization of membrane structural elements and of biochemical events carried out by or in membranes. As regards mitochondria, the interaction of the inner membrane components in carrying out electron transport and oxidative phosphorylation is the focal investigative question both for mitochondrial function and for the organization of vectorial events in general. 

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Nucleus, Mitochondria, Chloroplasts, Endoplasmic reticulum, Golgi apparatus. Vacuole... 

Golgi apparatus A system of flattened membrane-bounded vesicles often stacked into a complex. Numerous small vesicles are found peripheral to the Golgi and contain secretory material packaged by the Golgi. Involved in the packaging and processing of macromolecules for secretion and for delivery to other cellular compartments. 

Golgi apparatus, endoplasmic reticulum, ribosomes, lysosomes, peroxisomes, and cytoskeleton... 

COPI vesicles mediate anterograde transport from the intermediate compartment to the Golgi, transport within the Golgi apparatus and retrograde transport back from the Golgi to the ER by the recruitment of soluble... 

The Golgi apparatus is a stack of flattened vesicles that functions in posttranslational processing and sorting... 

Once the proteins have passed the quality control system of the early secretory pathway, they are transported in vesicles via the individual compartments of the Golgi apparatus to the plasma membrane. Soluble proteins are transported in the vesicle lumen, membrane proteins are integrated in the vesicle membrane. The transport to the cell surface is the default pathway for secretory and membrane proteins. Proteins may also become part of one of the intracellular compartments along the secretory pathway, but only if they contain specific retention signals. 

Disorders caused by the impairment of the Golgi apparatus and further vesicular trafficking (e.g., mutations in the Rab escort protein Repl leading to choroideremia). 

In contrast to the small transmitter molecules, the neuropeptides are synthesized in the rough endoplasmic reticulum of the neuronal perikarya. They are enclosed in vesicles in the Golgi apparatus. The vesicles travel down to the terminals by axonal transport. 

Figure 7. Video-enhanced DIC microscopy of rat liver Golgi apparatus membrane networks moving along microtubules using Xenopus egg microtubule motors (Allan and Vale, 1994). Top panel membrane extension with a bulbous terminus (arrow) attached to a microtubule (arrow heads). Middle panel same field two seconds later. The membrane has advanced about 3 pm along the microtubule (arrow). Bottom panel membrane has now advanced further along the microtubule (arrow). Bar = 2 pm.

Histamine is a critical mediator in anaphylactic reactions. It is a diamine produced by decarboxylation of the amino acid histidine in the Golgi apparatus of mast cells and basophils. Once secreted, it is rapidly metabolized by histamine methyltransferase [2]. Plasma histamine levels are elevated in anaphylaxis, reaching a concentration peak at 5 min and declining to baseline by 30-60 min [3]. Therefore, histamine samples for assessing an anaphylactic reaction should be obtained within 15 min of the onset of the reaction. Urinary metabolites of histamine may be found for up to 24 h. 

Sphingomyelins (Figure 14—11) are phosphohpids and are formed when ceramide reacts with phos-phatidylchohne to form sphingomyelin plus diacylglyc-erol (Figure 24-8A). This occurs mainly in the Golgi apparatus and to a lesser extent in the plasma membrane. 

Figure 25-2. The formation and secretion of (A) chylomicrons by an intestinal cell and (B) very low density lipoproteins by a hepatic cell. (RER, rough endoplasmic reticulum SER, smooth endoplasmic reticulum G, Golgi apparatus N, nucleus C, chylomicrons VLDL, very low density lipoproteins E, endothelium SD, space of Disse, containing blood plasma.) Apolipoprotein B, synthesized in the RER, is incorporated into lipoproteins in the SER, the main site of synthesis of triacylglycerol. After addition of carbohydrate residues in G, they are released from the cell by reverse pinocytosis. Chylomicrons pass into the lymphatic system. VLDL are secreted into the space of Disse and then into the hepatic sinusoids through fenestrae in the endothelial lining.

Figure 46-1. Diagrammatic representation of the two branches of protein sorting occurring by synthesis on (1) cytosolic and (2) membrane-bound polyribosomes. The mitochondrial proteins listed are encoded by nuclear genes. Some of the signals used in further sorting of these proteins are listed in Table 46-4. (ER, endoplasmic reticulum GA, Golgi apparatus.)...

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