Chapter 12 Processing pre-mRNA and Nuclear Transport By: Rachael Hattrup.

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?????