Transcript Document
Last Class Summary • • • DNA repair DNA general recombination DNA site-specific recombination • • RNA Processing Polymerase, Promoter, enhancer, transcription factor, transcription activator 5’ capping, splicing, 3’ cleavage and polyadenylation • • From RNA to Protein The Genetic Code The Reading Frames tRNA tRNA and mRNA pairing The chemically modified tRNA Amino Acid Activation Structure View Two Steps Hydrolytic Editing tRNA synthetases Hydrolytic Editing DNA polymerase Protein synthesis Ribosome On endoplasmic reticulum, or free Ribosome binding sites Translation: 1. Position at A 2. Peptidyl transferase to transfer peptide to tRNA at A site 3. Conformational change of large unit and mRNA on small unit. Elongation Factor enhances accuracy Ribosome Ribosome Reaction Mechanism for Protein Synthesis The Initiation Phase of protein synthesis in eucaryotes Eucaryotic initiation factors eIFs Bacterial one mRNA several gene Eucaryotes one mRNA, one gene. Stop codon Human tranlation release factor and tRNA Multiple Copies on the Same mRNA Rescue the incomplete mRNA process and add labels for proteases Incorporation of selenocysteine into a growing polypeptide chain Folding of the proteins Molten Globule Folding process starts at ribosome Protein Folding Pathway Molecular Chaperone An example of molecular chaperone functions Hsp70, early An example of molecular chaperone functions Hsp60-like protein, late The Fate of Proteins after translation Proteasome Ubiquitin E1: ubiquitin activating enzyme; E2/3: ubiquitin ligase Protein aggregation and human disease Cross-beta filaments The production of proteins Summary • RNA translation, tRNA, ribosome, start codon, stop codon • Protein folding, molecular chaperones • Proteasomes, ubiquitin, ubiqutin ligase • Protein aggregation • Control of Gene Expression • DNA-Protein Interaction Neuron and lymphocyte Experiment to show that the differentiated cell contains al the genetic information Differences in mRNA expression in different cancer cells Differences in Protein expression in different cancer cells Red: common; Blue: specific Six Steps at which eucaryotic gene expression are controlled Double helix Structure The outer surface difference of base pairs without opening the double helix DNA recognition code DNA bending induced by protein binding Helix-turn-Helix Proteins contain Helix-turn-Helix Homeodomain Protein is a special class utilizing helix-turn-helix Zinc Finger Motifs An Example protein utilizing Zinc Finger Motif B-sheets can also recognize DNA Leucine Zipper Dimer Homodimers and heterodimers can recognize different patterns Covalently-joint dimer Helix-loop-Helix dimer Single truncation of HLH inhibits binding One of the most Common protein-DNA interaction Six Zinc Finger motifs and their interaction with DNA Gel-mobility shift assay DNA affinity Chromatography Assay to determine the gene sequence recognized by a specific protein Chromatin Immunoprecipitation In vivo genes bound to a known protein Summary • Helix-turn-Helix, homeodomain, leucine zipper, helix-loop-helix, zinc-finger motif • Homodimer and heterodimer • Techniques to identify gene sequences bound to a known protein or proteins bound to known sequences