Ch. 18 - Post-transcriptional Regulation in Eukaryotes

Klug - Concepts of Genetics 12th Edition

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Klug 12th Edition

Ch. 18 - Post-transcriptional Regulation in Eukaryotes

문제 20

18장, 문제 20

How is it possible that a given mRNA in a cell is found throughout the cytoplasm but the protein that it encodes is only found in a few specific regions?

검증된 단계별 안내

Understand that mRNA molecules can diffuse or be transported throughout the cytoplasm after they are transcribed in the nucleus, allowing them to be widely distributed within the cell.

Recognize that protein localization is often controlled post-translationally, meaning that even if the mRNA is everywhere, the protein may only be synthesized or stabilized in specific regions.

Consider mechanisms such as localized translation, where ribosomes translate the mRNA only in certain parts of the cytoplasm, often guided by signals in the mRNA sequence or by cellular structures.

Explore the role of protein targeting signals and cellular transport systems that direct the newly synthesized protein to specific locations, or degrade it elsewhere, resulting in spatially restricted protein presence.

Summarize that the discrepancy between mRNA distribution and protein localization arises from cellular processes controlling where and when the protein is made, modified, or maintained, despite the mRNA being widespread.

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mRNA Localization and Transport

mRNA molecules can be distributed broadly within the cytoplasm, but their localization signals and transport mechanisms often direct them to specific cellular regions. This spatial regulation ensures that proteins are synthesized near their site of function, even if the mRNA is present elsewhere.

Localized Translation

Translation of mRNA into protein can be spatially regulated, occurring only in certain parts of the cell. This means that although mRNA is widespread, the protein is produced only where translation machinery is activated or where specific factors promote protein synthesis.

Protein Targeting and Anchoring

After synthesis, proteins can be transported or anchored to specific cellular compartments or structures. This selective localization restricts the protein’s presence to particular regions, explaining why the protein is found only in certain areas despite widespread mRNA distribution.

관련 실천

교과서 질문

What role do ubiquitin ligases play in the regulation of gene expression?

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교과서 질문

How and why are eukaryotic mRNAs transported and localized to discrete regions of the cell?

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교과서 질문

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교과서 질문

How may the covalent modification of a protein with a phosphate group alter its function?

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교과서 질문

How are mRNAs stored within the cell in a translationally inactive state, and how can their translation be stimulated?

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교과서 질문

While circular RNAs were first described long ago, they have only recently been investigated for function. What are their known and suspected functions in the cell?

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