lec6proteintransportmtsmoother

Molecular Biology of the Cell

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Unformatted text preview: PROTEIN SORTING / Trafficking PROTEIN Chapter 11 & 12 Test 2 - Outline Test Chapter 10- Membrane Structure/Proteins Chapter 11 – Transport (small molecules) Chapter 12- Protein Sorting Protein Folding / Ubiquitin Pathway CFTR – Ubiquitin Paper Test 2 October 14th. Relative Volumes of Intracellular Compartments Compartments A Cytosol B Endosomes C ER – rough cisternae D ER – smooth cisternae ER + Golgi apparatus Golgi E Lysosomes F Mitochondria G Nucleus H Peroxisomes 54 ? ? ? ? ? ? ? Cytosol Cytosol occupies 54% of total volume in liver cell in What What compartment ranks next in proportion of cell volume occupied? Relative Volumes of Intracellular Compartments Compartments A Cytosol B Endosomes C ER – rough cisternae D ER – smooth cisternae ER + Golgi apparatus Golgi E Lysosomes F Mitochondria G Nucleus H Peroxisomes 54 1 9% 6% 1 22% ? 1 Cytosol Cytosol occupies 54% of total volume in liver cell in What What compartment ranks next in proportion of cell volume occupied? Relative Amount of Intracellular Membranes Relative A B C D E F G H Endosomes ER – rough & smooth Golgi apparatus Lysosomes Mitochondria Nucleus Plasma membrane Peroxisomes Secretory vesicles ? ? ? ? ? ? ? ? ? What What membrane listed has the greatest proportion of membrane in the cell? the Relative Amount of Intracellular Membranes Relative A B C D E F G H Endosomes ER – rough & smooth Golgi apparatus Lysosomes Mitochondria- outter Mitochondria- inner Nucleus Plasma membrane Peroxisomes Secretory vesicles ? 35+16 7 ? 7 32 ? 2 0.4 ? What What membrane listed has the greatest proportion of membrane in the cell? the Advantages of Internal Membranes Advantages Segregation of cytoplasm Segregation for specialized functions for Some cellular reactions Some incompatible incompatible • Protein Protein synthesis/degradation synthesis/degradation synthesis in cytosol degradation in degradation lysosomes lysosomes • Oxidative reactions in Oxidative peroxisomes peroxisomes Protein Trafficking- Outline Protein 1. Gated transport: nuclearpores act 1. Gated nuclearpores as special gates that actively transport specific macromolecules transport Chapter 12 2. Transmembrane transport: 2. Transmembrane transport of specific protein across a membrane membrane -A. mt and chloroplast -B. primarily into the ER Chapter 12 3. Vesicular Transport: a membrane Vesicular membrane enclose a protein and moves it to a particular location particular Takes care of the majority of protein Takes trafficking issues trafficking Chapter 13 Protein Trafficking- Outline Protein 1. 1. Gated transport: Gated Chapter 12 1. Transmembrane transport: Chapter 12 Chapter 12 3. Vesicular 3. Vesicular Transport: - Nuclear Envelope and ER Nuclear 1. Gated transport: 1. nuclearpores act as nuclearpores special gates that actively transport specific macromolecules macromolecules Fig 12-9, MBOC4 2. Transmembrane transport: transport of specific protein across a membrane specific - A. mt and chloroplast A. - B. primarily into the ER (more later) - usually as an unfolded protein- Eventually usually folded once enters organelle (Mt,Cp, ER). folded After enters ER protein are then transport After by Vesicles to other organelles. by - Not Encoded by Human Mitochondrial Not DNA: DNA: RNA polymerase RNA processing and modifying enzymes RNA DNA replication enzymes Ribosomal proteins Some enzymes associated with CAC Some cycle cycle Main Point Not all proteins needed by the Main Protein Transport to: Protein Mitochondria Chloroplasts Post-translational terminal signal peptide Signal peptide cleaved Energy required Energy Post-translational terminal signal peptide Signal peptide cleaved Energy required th Requires Translocator Protein Import By Mitochondria Protein Protein Made in cytosol and then transport – (Post Translational) Protein (Post Fig 12-26, MBOC4 The Postage Stamp Signal Peptide (Sequence) or Signal Patch Signal Fig 12-8, MBOC4 Genetic Engineering to Study Signal Peptides Panel 12-1, MBOC Typical Signal Sequences Typical Function of signal Function peptide peptide Import into ER Return to ER Import into Import mitochondrion mitochondrion Import into plastid Example of Signal Sequence H3N-Met-Met-Ser-Phe-Val-Ser-Leu-Leu-LeuVal-Gly-Ile-Leu-Phe-Trp-Ala-Thr-Glu-Ala-GluGln-Leu-Thr-Lys-Cys-Glu-Val-Phe-Gln--+ --Lys-Asp-Glu-Leu-COOH3N-Met-Leu-Ser-Leu-Arg-Gln-Ser-Ile-Arg-PhePhe-LysPro-Ala-Thr-Arg-Thr-Leu-Cys-Ser-SerArg-Tyr-Leu-Leu+ H3N-Met-Val-Ala-Met-Ala-Met-Ala-Ser-Leu-GlnSer-Ser-Met-Ser-Ser-Leu-Ser-Leu-Ser-Ser-AsnSer-Phe-Leu-Gly-Gln-Pro-Leu-Ser-Pro-Ile-ThrLeu-Ser-Pro-Phe-Leu-Gln-Gly+ Table 12-3, MBOC General: nuclear membrane, ER, Golgi all same (interconnected) system all . Endoplasmic Reticulum (ER) (endo= within; -reticulum,= a network) A. Structure 1. single membrane continuous w/ nuclear 1. membrane 2. shape: network of mostly flattened sacs • • • a. sacs = cisternae (-na) a. cisternae 1) inside = cisternal space or ER lumen 1) cisternal ER 2) divides cytoplasm into 2 parts Protein Trafficking Protein 1. Gated transport: nuclearpores act as special Gated nuclearpores gates that actively transport specific macromolecules macromolecules 2. Transmembrane 2. transport: transport of transport transport specific protein across a membrane membrane -A. mt and chloroplast -B. primarily into the ER 3. Vesicular Transport: a membrane enclose a protein and moves it to a particular location protein Takes care of the majority of protein trafficking Takes issues issues - General: nuclear outer membrane, ER, Golgi all same membrane system all Endomembrane System What are the structural and functional What and differences between rough and smooth endoplasmic reticulum? (RER/SER) endoplasmic List the functions of each What are the most important similarities What between these compartments? between Smoother ER Functions? Smoother 1. membrane biogenesis 1. 2. Steroid Hormone synthesis 2. 3. Drug Detoxification 4. Glycogen catabolism 5. Ca storage (muscle) A. Membrane Biogenesis A. Usually minor component 1. phospholipids originate in ER, 1. A. plasma membrane • a. transferred to Golgi via transition vesicles a. • b. then exported to plasma membrane via secretory vesicles b. which fuse with the plasma membrane which B. nuclear membrane is connected to ER C. mitochondria & chloroplasts • much of the lipid is transferred to mitochondria & chloroplasts much via soluble cytoplasmic proteins called lipid transfer proteins or exchange proteins. 2. Synthesize lipid-based compounds, 2. e.g. steroid hormone biosynthesis e.g. • ex: male and female sex hormones 3. Detoxify lipid-soluble compounds • • • hydroxylation reactions (= addition of -OH) liver common tissue for detoxification modifies lipid soluble compounds to make water modifies soluble; then excreted in urine soluble; Smooth ER/ Example Smooth 3. Drug Detoxification drug detoxification example: Phenobarbital • a) injection of phenobarbital results in rapid a) increase in a mono-oxygenase (a barbiturateincrease detoxifying enzyme) in liver. • -hydroxylation of drug makes it more soluble in -hydroxylation water. Water soluble compounds are more easily “flushed” by the body. “flushed” • b) followed by a dramatic increase in smooth ER drug detoxification (cont.)/ Smooth Smooth ER c) effect is that a greater amount of c) drug needed for same effect drug d) the monooxygenase that is induced d) by phenobarbital ALSO hydroxylates other drugs (some useful) (1) e.g. antibiotics (narcotics, steroids, anticoagulants) Thought Question Thought How could widespread phenobarbital use in a population affect our ability to control disease? 4. Glycogen catabolism 4. one function of liver is to convert glycogen to one glucose glucose 1) in liver, glucose is stored as glycogen: 1) 2) converted to glucose to keep blood 2) sugar concentrations level sugar glycogen glucose-1-P Glucose-6-P glycogen • but, membranes generally but, impermeable to phosphorylated sugars sugars 1 2 3 3) in ER: G-6-P (glucose-6phosphatase) Glucose + Pi phosphatase) • then glucose can be transported into then blood blood 5. Calcium Storage 5. Requires an ATP- dependent Ca pump Requires (active process) (active Sarcoplasmic reticulum found in muscle cells Sarcoplasmic found • Type of ER that specifically stores CA • Only in certain types of cells Protein Trafficking Protein 1. Gated transport: nuclearpores act as special Gated nuclearpores gates that actively transport specific macromolecules macromolecules 2. Transmembrane 2. transport: transport of transport transport specific protein across a membrane membrane -A. mt and chloroplast -B. primarily into the ER 3. Vesicular Transport: a membrane enclose a protein and moves it to a particular location protein Takes care of the majority of protein trafficking Takes issues issues - ...
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