1. Roadmap of
protein traffic
inside cell

2. Two ways in which a sorting signal can be built into a protein

3. Some typical signal sequences

5. Nuclear Pore complexes perforate the nuclear envelope

6. Nuclear pore complexes

7. Nuclear side of the nuclear envelope

8. Face on view of nuclear complexes without the membrane

9. Side view of 2 nuclear pore complexes

10. Transport through nuclear pore complexes occurs through free diffusion and active transport

11. Nuclear import signal direst proteins to the nucleus

12. Single amino acid mutation in signal will prevent import into the nucleus

13. Nuclear import receptors bind to nuclear porins and nuclear localization signal of cargo protein
Different nuclear localization signals bind different import receptors

14. Ran GTP provides energy for nuclear protein import

15. Ran-GTP controls cargo loading and unloading

16. Transmembrane transport into the mitochondria and chloroplasts

17. Subcompartments of mitochondria and chloroplasts

18. Signal sequence for mitochondrial import
red = positively charged
yellow = nonpolar

19. Signal sequence for mitochondrial import can form amphipathic α - helix
α - helix is recognized by receptor proteins

20. Protein translocators in mitochondrial membrane

21. Protein import by mitochondria

22. DVD Clip 55

24. Protein transport into the peroxisomes

25. Roadmap of
protein traffic
inside cell

26. Insertion of rhodopsin into the ER membrane

27. Most proteins in the ER
are glycosylated
Proteins in cytosol are
rarely glycosylated
original precursor
oligosaccharide added
to most proteins in the ER

28. Protein glycosylation in the rough ER

29. Oligosaccharides are used as tags to mark the state of protein folding

30. Misfolded proteins are exported from ER and destroyed