Đang chuẩn bị nút TẢI XUỐNG, xin hãy chờ
Tải xuống
Ribosomes synthesize proteins by reading the nucleotide sequence of mRNAs and polymerizing amino acids in an N→C direction. In this chapter, the following content will be discussed: How is the nucleotide sequence of an mRNA molecule translated into the amino acid sequence of a protein molecule? | Chapter 33 Protein Synthesis and Degradation to accompany Biochemistry, 2/e by Reginald Garrett and Charles Grisham All rights reserved. Requests for permission to make copies of any part of the work should be mailed to: Permissions Department, Harcourt Brace & Company, 6277 Sea Harbor Drive, Orlando, Florida 32887-6777 Outline 33.1 Ribosome Structure and Assembly 33.2 Mechanics of Protein Synthesis 33.3 Protein Synthesis in Eukaryotes 33.4 Inhibitors of Protein Synthesis 33.5 Protein Folding 33.6 Post-Translational Processing of Proteins 33.7 Protein Degradation Ribosome Structure and Assembly E. coli ribosome is 25 nm diameter, 2520 kD in mass, and consists of two unequal subunits that dissociate at < 1mM Mg2+ 30S subunit is 930 kD with 21 proteins and a 16S rRNA 50S subunit is 1590 kD with 31 proteins and two rRNAs: 23S rRNA and 5S rRNA These ribosomes and others are roughly 2/3 RNA 20,000 ribosomes in a cell, 20% of cell's mass Ribosomal Proteins One of each per ribosome, except L7/L12 with 4 L7/L12 identical except for extent of acetylation at N-terminus Four L7/L12 plus L10 makes "L8" Only one protein is common to large and small subunits: S20 = L26 Little known of structures - these proteins are insoluble and difficult to study Ribosome Assembly/Structure If individual proteins and rRNAs are mixed, functional ribosomes will assemble Gross structures of large and small subunits are known - see Figure 33.3 A tunnel runs through the large subunit Growing peptide chain is thought to thread through the tunnel during protein synthesis Eukaryotic Ribosomes Mitochondrial and chloroplast ribosomes are quite similar to prokaryotic ribosomes, reflecting their supposed prokaryotic origin Cytoplasmic ribosomes are larger and more complex, but many of the structural and functional properties are similar See Table 33.2 for properties Mechanics of Protein Synthesis All protein synthesis involves three phases: initiation, elongation, termination Initiation involves binding . | Chapter 33 Protein Synthesis and Degradation to accompany Biochemistry, 2/e by Reginald Garrett and Charles Grisham All rights reserved. Requests for permission to make copies of any part of the work should be mailed to: Permissions Department, Harcourt Brace & Company, 6277 Sea Harbor Drive, Orlando, Florida 32887-6777 Outline 33.1 Ribosome Structure and Assembly 33.2 Mechanics of Protein Synthesis 33.3 Protein Synthesis in Eukaryotes 33.4 Inhibitors of Protein Synthesis 33.5 Protein Folding 33.6 Post-Translational Processing of Proteins 33.7 Protein Degradation Ribosome Structure and Assembly E. coli ribosome is 25 nm diameter, 2520 kD in mass, and consists of two unequal subunits that dissociate at < 1mM Mg2+ 30S subunit is 930 kD with 21 proteins and a 16S rRNA 50S subunit is 1590 kD with 31 proteins and two rRNAs: 23S rRNA and 5S rRNA These ribosomes and others are roughly 2/3 RNA 20,000 ribosomes in a cell, 20% of cell's mass Ribosomal Proteins One of each per ribosome, except .
