1. Compartments and Information Flow between Nucleus & Cytoplasm Lecture 18 BSCI 420/421 Oct 14, 2002 “Your future is ahead of you” - Yogi Berra 1. Compartments of Eukaryotic cells 2. Information flow between Nucleus and cytoplasm

2. Compartments of a eukaryotic cell

3. Compartments of an animal cell

4. Flow chart of Eukaryotic cell

8. Molecules smaller than 9 nm or 60 KDa can enter nuclei by passive diffusion thru pores. Larger must have Nuclear Localization Signals (NLS) and be actively transported in.

9. Importance of NLS SV40 T-antigen With normal or Mutant NLS in infected cells. T-antigen detected by fluor Anti-T

10. The cycle of Ran, a monomeric G protein, gives directionality to nuclear import and export. Ran GTPase activating protein Is cytosolic and Ran Guanine nucleotide exchange factor is Nuclear.

11. Structure of Ran-GTP & How its binding to import receptor leads to release of cargo protein

12. Nuclear import andexport depend on receptors & Ran cycle

13. Nuclear transport of Dorsal TF protein determines ventral cells From dorsal cells in Drosophila embryos Toll cell surface receptors are Activated by ventral signals, which leads to phosphorylation of an Inhibitor, cactus. This causes cactus to be degraded, exposing the NLS on Dorsal, which enters the nucleus.