IUB BIOL-L 211 - Protein Sorting and Localization (4 pages)

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Protein Sorting and Localization

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Protein Sorting and Localization


Antibiotics, Article, Protein Sorting and Localization

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Indiana University, Bloomington
Biol-L 211 - Molecular Biology
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BIOL L211 Lecture 33 Outline of Last Lecture I Translation Elongation II Translation Termination Outline of Current Lecture I Antibiotics II Article III Protein Folding IV Protein Targeting Eukaryotes Current Lecture Protein Sorting and Localization I Antibiotics A Antibiotics are found in the environment and fight bacterial infection 1 Also can target eukaryotic cells B Resistance has led to increased research and development of antibiotics C Around 40 work by a mechanism that targets ribosomes and affects translation D Puromycin Mechanism 1 Inserts into A site 2 Becomes a target for peptide bond formation 3 Polypeptide chain is transferred to Puromycin 4 No more amino acids can be added 5 Truncated protein dissociates now ineffective II Article These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute A Mapping the Human Proteome The Scientist B Human Protein Atlas 1 Interactive database of millions of maps of around 20 000 different proteins in the body 2 Data collected using fluorescently tagged antibodies that mark proteins a Visualized with microscopy b Analyzed with other techniques C Maps compared between healthy tissues and cancer tissues D Most proteins in the study are common to all cells E 2000 proteins are unique to certain tissues F Testes have largest number of unique proteins thus far 999 III Protein Folding A Recall formation of primary secondary tertiary and quaternary structure B Chaperone Proteins promote correct protein folding 1 GroEL chaperone found in some bacteria a Two subunits in barrel like structure 2 GroES additional chaperone found in some bacteria b Forms a lid for GroEL C GroEL GroES Mechanism 1 Partially folded protein enters GroEL barrel 2 ATP aids in binding the GroES cap to the GroEL barrel 3 Protein is properly folded 4 ATP hydrolysis releases the properly folded protein and GroES IV Protein Targeting Eukaryotes A 3 options for proteins 1 Remain in cytoplasm 2 Targeted for secretion 3 Transported to a specific organelle B Protein Localization Sorting Motif like a zip code that identifies a protein s target location 1 Found at N terminus C terminus or both 2 Nuclear Localization Sequence a 5 10 basic positively charged amino acids signal that a protein is for the nucleus 3 Endoplasmic Reticulum Retention Sequence a KDEL Lys Asp Glu Leu b If this sequence remains proteins will not leave ER C Endomembrane System different membranes suspended in the cytoplasm 1 Nuclear envelope ER Golgi apparatus lysosomes vacuoles vesicles and cell membrane 2 Connected directly or via vesicles 3 Proteins enter endomembrane system via ER target destination with sorting motif D Endoplasmic Reticulum ER 1 Continuous with nuclear envelope 2 Cisternae system of connected sacs and tubules of ER also stacks of membranes in the Golgi apparatus 3 Rough ER has ribosomes on cytoplasmic side and involved in protein synthesis and folding 4 Smooth ER no ribosomes and helps synthesize lipids E Targeting to ER 1 Signal Recognition Particle SRP recognizes and binds the translated signal sequence halting translation 2 Ribosome and polypeptide brought to a receptor in ER membrane by SRP 3 Once SRP leaves translation resumes and the polypeptide enters the ER via translocation complex 4 Proteins in the ER have their signal sequences removed then are part of endomembrane system F The Golgi apparatus 1 Modifies sorts and packages proteins for export like FedEx 2 Consists of cisternae 3 Proteins are incorporated into transport vesicles in the ER a Those vesicles dock along the cis face of the Golgi apparatus b Proteins dumped into the Golgi 4 CIsternae perform protein modifications 5 At trans face of Golgi proteins packaged into membrane vesicles or secretory vesicles 6 From there they are sent to their various destinations in cell out of cell

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