chapter 12 processing pre-mrna and nuclear transport by: rachael hattrup
TRANSCRIPT
Chapter 12Processing pre-mRNA and
Nuclear TransportBy:
Rachael Hattrup
Processing of eukaryotic Pre-mRNA
1) 5’ capping with 7-methylguanosine2) 3’cleavage at Poly (A) site3) Polyadenylation added
1) 250 in mammals2) 150 insects3) 100 yeasts
4) RNA splicingIntrons removed and exons kept.
5’ Capping
Overview of mRNA processing in Eukaryotes
Macromolecular Transport into Nucleus
• Nuclear envelope
• Nuclear Pores– Nuclear pore complex (NPC)– Nucleoporins
Nuclear Pore Complex
Macromolecular Transport into Nucleus
1) 2 Importins bind to create nuclear-import receptor
2) -Importin binds to Nuclear-localization signal (NLS) of “cargo” protein
2) -importin interacts with FG nuclear proteins to diffuse through NPC
Macromolecular Transport into Nucleus cont…
3) Ran-GTP interacts with importins causing conformational change creating less affinity for NLS
4) Ran-GTP transports importin out to cytoplasm
Transport into Nucleus
Macromolecular Transport out of Nucleus
1) Protein exportin 1 binds to Nuclear-export signal (NES) bound to “cargo” protein and Ran-GTP
2) Difusses through NPC
3) Ran-GTP converted to Ran-GDP releasing the complex
Transport out of Nucleus
The End
Questions?????