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17 Cards in this Set
- Front
- Back
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Golgi Structure |
Mammalian cells has 1 large Golgi complex Plant and yeast cell have numerous Golgi complexes. Smooth, flattened disk-like membrane-bound bound cisternae. Specific polarity/orientation (cis Golgi network (CGN), cis cistern, medial cisternae, trans cistern, trans Golgi network (TGN) Supported by protein-based scaffold It is organized into stacks mediated by the Golgi matrix Consists of various Golgi peripheral and integral membrane proteins . Cytosolic-facing domains interact to form a 'scaffold - link CGN, cisternae and TGN together |
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GRASPs |
GRASPs serve as 'tethering;' to link different Golgi sub compartments together - Depletion of Grasp55/65 results in the disable of the Golgi complex. |
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Golgins |
long filamentous proteins that tether various parts of the Golgi to the cytoskeleton and other sub cellular structures. |
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Golgi matrix proteins |
Links the Golgi Complex to the cytoskeleton. Positions and movement of the Golgi complex (like all organelles) within the cell is controlled by its interaction with the cytoskeleton |
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GMAP |
GMAP-210 facilitates ER to cis-Golgi communication via direct interaction with the microtubules between two organelles |
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cis Golgi network (CGN) |
located at the cis face of the Golgi complex consists of an interconnected network of tubules and vesicles adjacent to the ERES serves as a sorting station destination (recipients compartment ) of COPII vesicles from the ERES and site of COPI vesicle assembly for retrograde transport to the ER OR anterograde transport as the CGN matures into the rest of the Golgi complex |
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Golgi cisternae |
series of three or more large flattened cisternae making up the majority of the organelle divided into three main sections (cis, medial, trans) site where golgi metabolism occurs and modification (like glycosylation) |
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trans Golgi network (TGN) |
located on the trans face (side) of the Golgi complex interconnected network of tubules and vesicles serves as a sorting station involved in the retrograde transport of materials from the Golgi to other compartments in the endomembrane system site of clatherin vesicle assembly for transport to the endosome/lysosome site of secretory vesicle/granule assembly for transport to the plasma membrane site of copI vesicle assembly for transport (retrograde transport) back to the trans cisternae |
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Functions of Golgi Complex |
processing plant of the cell synthesis of complex polysaccharides (components of extracellular Matrix and cell walls) Modification of proteins and lipids (glycosylation and proteolytic modification) Transport and sorting of proteins transport from ER to Golgi to PM as anterograde transport from PM to Golgi or Golgi to ER retrograde sorting of proteins typically occur at either TGN or TGN |
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Glycosylation |
Most glycoproteins (synthesized and N-linked-glycosylated in the RER) moving through the Golgi complex (cis -> trans) are subjected to additional glycosylation reactions cis, medial and trans Glogi cisternae possess unique glycosyltransferase enzymes sequentially modify the glycoprotein's core oligosaccharides in specific ways. |
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N-linked glycosyl group modification |
lysosomal proteins arrives in CGN from RER In cis Golgi cisternae - mannose phosphorylated. The enzyme recognizes a signal patch in the proteins. N-acetylglucosamine-1-phosphate is transferred to a specific mannose residue from a nucleotide sugar door. In medial Golgi, N-acetylglucosamine group removed and lysosomal enzyme now contains mannose-6-phosphate group the protein is recognized by Mannose-6-phosphate receptor (MPRs in TGN to sort Enzyme to lysosome |
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Glycosylation in cis cisternae and TGN |
In cis cisternae 2 mannose sugars in the core oligosaccharide are phosphorylated
in the TGN cargo proteins with mannose-6-phosphate (M6P groups are packaged into lysosomal-destined transport vesicles cargo proteins without M6P are packaged and sent into other TGN transport vesicles or granules destined for the PM |
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N-linked oligosaccharides vs O-linked oligosaccharides |
N-linked synthesis begins in ER O-linked synthesis/modification occurs entirely in Golgi |
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Vesicular transport model |
The least favoured model cargo is carried in an anterograde direction via transport vesicles the composition of each subcompartment changes with the coming new membrane and cargo the golgi complex persists overall because transport vesicles (COPI) continually move residents Golgi proteins back to the proper sub compartment |
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Cisternal progression/ maturation model general |
most favoured today. Golgi sub compartments are considered dynamic structures with each subcompartment continually moving from cis to trans the composition of each subcompartment changed from cis to trans through the stack (CGN matures into cis cisternae which matures into medial cisterane and so on. \ |
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Cisternal progression/ maturation model detail |
The golgi complex persists overall because transport vesicles continually move resident Golgi proteins back to proper sub compartmentsCOPII-coated transport vesicles from ER carrying cargo protein arrive at the cis face of the Golgi compound and incoming vesicles fuse together to form the new CGN The newly formed CGN begins to move forward into the complex stack and progressively matures into the cis cisternae Each cisternae matures into the next cisternae in the complex while moving through the complex, the chemical composition of each cisternae constantly changes COPI-coated vesicles transport resident Golgi enzymes back through the complex TGN eventually disperses into various types of vesicles and different vesicles deliver certain cargo from the TGn to different compartments in the endomembrane system. |
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Evidence of maturation model |
Vesicle identity and location |
