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Golgi complex László KŐHIDAI, PhD., Assoc. Prof. Department of Genetics, Cell- and Immunobiology Semmelweis University 2008.

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Presentation on theme: "Golgi complex László KŐHIDAI, PhD., Assoc. Prof. Department of Genetics, Cell- and Immunobiology Semmelweis University 2008."— Presentation transcript:

1 Golgi complex László KŐHIDAI, PhD., Assoc. Prof. Department of Genetics, Cell- and Immunobiology Semmelweis University 2008

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3 Camillo Golgi ( ) Nobel prize 1906

4 Structure Saccles Saccles Tubules Tubules Vesicles Vesicles structural-fumctional unit: dictyosome 4-6 saccles the structure is polarized into sub-compartments the structure is polarized into sub-compartments cis Golgimedial Golgi trans Golgi cis Golgimedial Golgi trans Golgi cis Golgi network (CGN) trans Golgi network(TGN)

5 Dictyosomes of the plant cells Synthesis of complex polysaccharides of the cell wall (hemicellulose, pectins)

6 Main functions transport transport sorting sorting transformation transformation membrane wrapping membrane wrapping

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8 Pulse-chase technique

9 CGN the peptides arrive from the ER in vesicles the peptides arrive from the ER in vesicles they are N-glycosilated they are N-glycosilated no sorting in the ER no sorting in the ER Bidirectional transport of proteins: soluble, endogenous proteins of the ER recycled soluble, endogenous proteins of the ER recycled in transport vesicles - retention signal is required in transport vesicles - retention signal is required sorting and transport of lysosomal enzymes sorting and transport of lysosomal enzymes

10 Sorting and modification of lysosomal enzymes Mannose-6-phosphate (M-6-P) signaling: based on the recognition of lysosomal hydrolases based on the recognition of lysosomal hydrolases recognition of the “signal patches” (proper 3D combination recognition of the “signal patches” (proper 3D combination of amino acids) is required of amino acids) is required main working enzyme: GlcNAc-phosphotransferase main working enzyme: GlcNAc-phosphotransferase Phosphorylation of the mannoses: promotes the sorting of these enzymes promotes the sorting of these enzymes prevents the further modifications prevents the further modifications

11 Glycosilation in the Golgi Modifications on the N-glycosilation pattern cis-Golgi: cis-Golgi: mannose-type oligosaccharides complex oligosaccharides TGN: TGN: substitution with sialic acids - negatively charged O-glycosilation: takes place mainly in the medial- and trans-Golgi takes place mainly in the medial- and trans-Golgi sidechains of Ser and Thr are glycosilated sidechains of Ser and Thr are glycosilated

12 Other modifications glucose-amino-glycane (GAG) chains glucose-amino-glycane (GAG) chains sulphatation (proteoglycanes, Tyr res. of peptides) - TGN sulphatation (proteoglycanes, Tyr res. of peptides) - TGN proteolytic modifications - secretion vesicle proteolytic modifications - secretion vesicle

13 Synthesis of lipids in the Golgi ceramideglycolipidssphingomyelin

14 Main transport pathways from TGN

15 endosomal-lysosomal compartment endosomal-lysosomal compartment via transport vesicles - M-6-P receptors surface membrane - secretion surface membrane - secretion constitutive secretion - transports lipids and peptide components of the surface membrane and the extracellular matrix exocytosis exocytosis regulated secretion

16 acid phosphatase trans Golgi network osmium reduction cis-Golgi unstained Enzyme content of different compartments in Golgi

17 Modifications of secretory vesicles selective aggregation - TGN selective aggregation - TGN further modifications and sorting further modifications and sorting inactive precursor - active enzyme or hormone (e.g. preproinsulin - proinsulin - insulin) concentration - loss of water concentration - loss of water hydratation - e.g. proteoglygans hydratation - e.g. proteoglygans uptake some cytoplasmatic substances e.g. histamine uptake some cytoplasmatic substances e.g. histamine

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19 Alternative pathways some molecules do not synthesized on the rER some molecules do not synthesized on the rER (e.g. interleukin 1  and 1  - IL1  -IL1 , (e.g. interleukin 1  and 1  - IL1  -IL1 , basic fibroblast growth factor-bFGF) basic fibroblast growth factor-bFGF) these molecules transported by ABC-transporters these molecules transported by ABC-transporters other roles of the alternative pathway: other roles of the alternative pathway: - elimination of toxic proteins - regulation of protein concentrations in cytosol

20 Defects of sorting mechanism lysosomal enzymes do not enter the late endosomes BUT enzymes enter the constitutive secretory pathway and released I (=inclusion) cell disease: - the M-6-P signal is not formen on the enzymes - lysosomal enzymes “escape” from the cell - deficient intracellular digestion - the non-digested substances form INCLUSIONS

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24 Network of membran flow in eukaryotic cells

25 Organell-dependent metabolism of lipids


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