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Unformatted text preview: 1 DNA RNA Protein Replication Transcription Translation Lecture 50: Translation II (protein synthesis) Todays lecture: Text pp. 1044-1058, 1101-1103 Preprinted lecture notes 86-96 Download from http://www.mbi.ufl.edu/facilities/msg/bch4024-notes.html Assembling the components Regulating translation Looking at large assemblies 1) mRNA is translated 5 3 2) Polypeptide chain synthesis is amino (NH 3 + ) carboxy (COO- ) 3) Three phases of the ribosome cycle a) Initiation: bind initiator tRNAAUG b) Elongation: bind aa tRNAs and form peptide bonds c) Termination Some general features of protein synthesis 2 Protein synthesis requires energy 1) From ATP 1) Charging aatRNA (requires two ATPs since ATP AMP) 2) Eukaryotic initiation 2) From GTP 1) For binding tRNA to ribosome 1) At initiation 2) During elongation 2) For translocation of peptidyl tRNA and growing protein chain (N-1 residues) 3) For termination (last residue) Estimated total (prokaryotes): 4 N ATP/GTP for a protein with N residues IF1 promotes mRNA binding IF2 initiator tRNA binding; binds GTP IF3 Anti-association activity; promotes accurate start & mRNA binding Initiator tRNA binds at P site on 30S Shine-Dalgarno sequences position initiation codon in vicinity of decoding site, P site Chain initiation IF Initiation Factor protein Ribosome is opened up to allow positioning of mRNA strand A aminoacyl site P peptidyl site E exit site 3...
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- Fall '08