1. Post-Translational Events I Translocation of Newly Synthesized Proteins into Membranous Organelles

2. Locations of Protein Synthesis ER Associated Ribosomes –proteins translocate co-translationally into ER lumen –subsequent processing & transport through Golgi for secretory vesicles and lysosomes Cytoplasmic Ribosomes –proteins translocated post-translationally into membranous organelles (except Golgi, ER and lysosome)

3. Transport of Cytoplasmically Synthesized Proteins Import into organelles (transmembrane and lumenal) –Mitochondrial import –Chloroplast import –Peroxisome import Translocation across plasma membrane Insertion in cytoplasmic face of plasma membrane

4. Signal Sequences Portions of protein sequence –Frequently N-terminal, C-terminal –Occasionally located within –Often cleaved following transport event Signal Recognition Particles/Complexes –protein-translocation channels –escort (chaperone) proteins

5. Mitochondrial Protein Import Four Destinations –Outer membrane –Innermembranous space –Inner membrane –Matrix TOMs –Translocase of the outer mitochondrial membrane TIMs –Translocase of the inner mitochondrial membrane Tiny TIMs –escorts of the innermembranous space

6. TOM & TIM Function

7. Tiny TIMs and TIM22

8. TOC & TIC

9. Peroxisome Import Signal sequence for recognition by PEX5 -SKL- COOH

10. Peroxisome Formation

11. Translocation of ER-Associated Ribosome Synthesized Proteins

12. Docking of Ribosomes to ER Signal peptides typically 10-20 residues – shorter than those on cytostolically synthesized proteins

13. Signal Recognition Particle Ribonucleoprotein complex Similar to bacterial SRP Ribosome binding Signal peptide binding translocation

15. Translocation of Various Classes of ER Proteins lumenal proteins Type 1 transmembrane proteins Type 2 transmembrane proteins multipass transmembrane proteins