Lecture #13: RNA Processing and Measurement

How do RNA strands leave the nucleus?

• Through nuclear pores

• Movement is mediated by specific transport proteins

Transcription and translation in prokaryotes

• Transcription and translation are couples and occur simultaneously in cytoplasm

• Termination of RNA synthesis occurs at a specific site; the intact RNA is then translated into proteins on ribosomes

Transcription and translation in eukaryotes

• Occur in different cellular locations

  • mRNA must be transported from the nucleus to cytoplasm before translation occurs

    • Transport to cytoplasm is also regulated

• Termination is not well understood, transcript undergroes several modifications before exporting cytoplasm for translation

Major types of RNA processing

• Addition of 5’ CAP

• Addition of a POLY A tail

• RNA splicing

How mRNA is capped

Function of 5’ CAP

• enhances transport of mRNA to cytoplasm by transport proteins

• enhances translation of mRNA

• protects mRNA from degradation

  • masks 5’ end from exo and endo ribonucleases