13: Post Transcriptional Regulation of Gene Expression
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- 13.1: Introduction
- The metabolic potential of cells is flexible, depending on various mechanisms that ultimately determine the levels and activities of proteins that dictate a cell’s metabolic state. We have seen some of these regulatory mechanisms. In this chapter, we look at different kinds of post-transcriptional regulation, events somewhere between mRNA transcription and controls on the activity of finished proteins. These control mechanisms are most diverse in eukaryotes.
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- 13.2: Post-transcriptional Control of Gene Expression
- Not too long ago we thought that very little of the eukaryotic genome was ever transcribed. We also thought that the only non-coding RNAs were tRNAs and rRNAs. Now we know that other RNAs play roles in gene regulation and the degradation of spent cellular DNA or unwanted foreign DNA. These are discussed in detail below.
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- 13.3: Eukaryotic Regulation of Translation
- In many respects, the overall process is similar to prokaryotic translation initiation described elsewhere. The 40S ribosomal subunit itself can bind to and scan an mRNA, seeking the start site of an ORF (open reading frame) encoding a polypeptide. When GTP-bound eukaryotic initiation factor 2 (GTP-eIF2) binds met-tRNAf, it forms a ternary complex (TC).
Thumbnail: N-linked protein glycosylation (N-glycosylation of N-glycans) at Asn residues (Asn-x-Ser/Thr motifs) in glycoproteins. (Public Domain; Kosi Gramatikoff ).