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12 Cards in this Set
- Front
- Back
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What are P-bodies?
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mRNA-processing
(P) bodies are specific cytoplasmic sites where mRNA turnover occurs, as either decay or storage. |
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What 2 features distinguish mature eukaryotic mRNA?
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The 5′ 7-methylguanosine cap and the 3′ poly(A) tail.
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What are the functions of the 5' guanine cap along with cytoplasmic proteins eIF4E?
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To protect the mRNA transript from 5'->3' exonuclease decay and for recognition by ribosomes to bind & begin translation.
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What is the purpose of the Poly-A tail along with poly-A binding proteins?
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to protect the mRNA transcript from 3'->5' exonuclease activity.
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How is mRNA decay initiated?
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Either the poly-A tail or the guanine cap must be compromised or the transcript cleaved by an endonulcease.
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What are polysomes?
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Two or more ribosomes that
are bound to different sites on the same mRNA |
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What is an exosome?
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A large complex of 3′→5′
exonucleases that functions in the nucleus and the cytoplasm in several different RNA processing and RNA degradation pathways. |
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What is the transcriptome?
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The pool of mRNAs that is
present in the cell under a given condition. |
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What is PAN2–PAN3?
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It is a PABP-dependent poly(A) nuclease (deadenylase) that is involved in trimming the poly(A) tails of nascent mRNAs to the standard length of 60–80 nucleotides in
S. cerevisiae. Mammalian PAN2–PAN3 carries out the initial shortening of the tail of a β-globin reporter transcript from the usual 200 nucleotides to a length of ~80 nucleotides. |
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What is CCR4-NOT?
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CCR4–NOT is the main deadenylase in S. cerevisiae and is a large complex of nine proteins. It is inhibited by PABP.
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What is PARN?
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poly(A)-specific ribonuclease is a unique deadenylase that it has cap-dependent
activity — that is, its processivity is enhanced by the presence of a 5′ cap on the mRNA |
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What is PARN's role in development?
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PARN has been implicated in the mass deadenylation of
maternal mRNAs that occurs in Xenopus laevis oocytes during maturation and is also the main deadenylase activity in cytoplasmic extracts derived from various cell lines. PARN is essential for embryogenesis in plants, and is found in many higher eukaryotes including mammals and several insect species |
