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Cell Biology 18 - Organelle 2 nd

Cell Biology 18 - Organelle 2 nd. Sung Youn Lee, PhD. Student Veterinary collage, Room 320 02 450 3719, 016 293 6059 leevet@paran.com. Membrane lipids. The synthesis of membrane phospholipids, cholesterol, and ceramide occurs within the ER, usually SER.

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Cell Biology 18 - Organelle 2 nd

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  1. Cell Biology 18- Organelle 2nd Sung Youn Lee, PhD. Student Veterinary collage, Room 320 02 450 3719, 016 293 6059 leevet@paran.com

  2. Membrane lipids • The synthesis of membrane phospholipids, cholesterol, and ceramide occurs within the ER, usually SER. • The synthesis of phospholipids occurs on the cytoplasmic leaflet of ER membrane. • Flippases ; newly synthesized phospholipids can be moved to the luminal leaflet of the ER. • ER--> target organelle • Bud-fusion ; Golgi, lysosome, plasma membrane • Protein (water soluble exchage protein) ; mitochondria and peroxisome

  3. phosphatydylcholine

  4. flippase

  5. Golgi apparatus • Function ; posttranslational modification and sorting of protein and lipids synthesized within ER. • Glycosylation (O-linked) • Insulin • CGN, cis-, medial-, trans-, TGN • Distribution of cis-Glogi network; • KEDL(ER retention signal) ; return it to ER • Distribution of trans-Glogi network; • Sort into different transport vescles destined for the lysosomes, plasma membranes, or secretion

  6. Targeting of acid hydrolases to the lysosome • The lysosomes contain acid hydroase – protease, nuclease, glycosidase, lipase, phospholipase, sulfase, and phosphatase • Acid hydrolases are active at pH 5.0, but inactive at neutral pH of the cytoplasm. • Acidic pH of the inner lysosome is maintained by an ATP-dependent proton pump in the lysosomal membrane. –V-class ATPase

  7. V-type ATPase

  8. 소각로 = lysosome ?

  9. Types of ATPase • P-class • Na+ K+ ; Na+3(out), K+2(in), animal tissue • Ca2+ ; maintain low Ca2+ in cytosol, myocyte (sarcoplasmic reticulum) • V-class • H+ ; lysosome(endosome) & vacule – highly acidic (pH 5.0-5.5) • ABC (ATP binding cassette) • MDR ATPase ; multidrug resistance ATPase • Cystic fibrosis transmembrane regulator

  10. Material for destruction • Phagocytosis – macrophage and neutrophil • Receptor mediated endocytosis – clathrin-coated pit • Autophagy – first wrapped with ER derived membrane and then fused with lysosome • KFERQ – selectively taken by lysosomes

  11. Proteolytic pathway • In addition to lysosomal destruction. The cytoplasm has several proteolytic enzymes. • Proteins have Met, Ser, Thr, Ala, Val. Cys, Pro, or Gly as their NH2-terminal amino acids are stabilized against proteolysis. • Others modified by binding of ubiquitin, linked to lysine at the NH2-termini --> to identify the substrate of ATP-dependent protease

  12. Protein and lipid destined for plasma membrane • Golgi retention signal ; membrane spanning α-helical segment of transmembrane proteins. • Constitutive secretion or exocytosis • no signal ; default pathway • Regulatory exocytosis • Require a chemical signal (Ca2+) • Targeting for plasma membrane • GPI ; TGN --> plasma membrane • Cytoplasm --> plasma membrane --> sort by endocytosis

  13. Internalize • Exocytosis adds new membrane to the plasma membrane. • Endocytosis-exocytotic cycle must be under tight control. • A macrophage ingests 3% of its plasma membrane per minute. • Endocytosis • Pinocytosis ‘ cell drinking’, 0.1~0.2um • Phagocytosis ‘cell eating’ 1.0um<, opsonin (Ig or Complement) – Fc receptor on the surface of macrophage and neutrophil, but complete coated with opsonin.

  14. Clathrin-coated pit

  15. Rapidly return to the plasma membrane

  16. Receptor mediated endocytosis #2 examples • First – Cholesterol • Cholesterol does not circulate in its free form, but as a component of 20nm spherical LDL particle • LDL receptor in their plasma membrane, causes its uptake by receptor mediated endocytosis. • Hypercholesterolema ; LDL receptors are not produced or defect the binding site

  17. Receptor mediated endocytosis #2 examples • Second-transferrin • Serum glycoprotein involved in transport of iron from liver and intestine to other tissue • Apotransferrin+Fe2+ --> ferrotransferrin • All cells contain ferrotransferrin receptors.

  18. Receptor recycle Transcytosis Receptor recycle

  19. Selective and Non-selective vesicle transport • Selective ; Clathrin-coated vesicle, TGN --> late endosome • Non-selective, constitutive ; coatmer coat, ER-->Golgi, between Golgi, Golgi --> Plasma membrane

  20. protein protein energy

  21. Monomeric G protein Protein ; composed of seven COPs

  22. Vesicle docking and fusion Vesicle Plasma membrane • synapsin Spectrin • VAMP t-SNAREs synaptotagmin (syntaxin & SNAP25) Complex • SNAP + NSF + ATP + Ca2+

  23. Vesicle Plasma membrane • synapsin Spectrin • VAMP t-SNAREs synaptotagmin (syntaxin & SNAP25) Complex • SNAP + NSF + ATP + Ca2+

  24. Thank you for your attention ~

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