Organization of the NPC
Specificity Models of the NPC Brownian GateSelective Phase‘Oily Spaghetti
Week 2: RNA maturation transport, & localization RNA export to the cytoplasm: model systems RNA degradation Links between RNA processing, transport, degradation RNA localization in the cytoplasm RNA processing: brief overview
Evidence for checkpoints? mRNA transport
Specific process for Pol II transcripts nuclear CBC binds to m 7 G-cap: role in splicing, transport, stability (exchanged in cytoplasm) Function in transport, stability, translation
CPSF: cleavage and polyadenylation specificity factor CStF: cleavage stimulatory factor CF: cleavage factor PAP: polyA polymerase PAB: polyA binding protein Function in transport, stability, translation
Compartments inside the nucleus 1. Nucleolus
2. Perichromatin granule clusters Carter et al., Science (1993) 259: 1330
Balbiani Rings (Chironomus tentans)
SUMMARY I.Multiple steps of mRNA biosynthesis are tightly coupled II.Mex67/TAP is one major mRNA export factor Binding to mRNA may already occur at the site of transcription III.Many questions remain - How are mRNA substrates released in the cytoplasm? - Are there multiple mRNA export pathways? - How is processing and transport coupled? etc.