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32 Cards in this Set
- Front
- Back
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What classes of RNA does editing occur in? |
mRNA tRNA rRNA |
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What are the two types of RNA editing? |
insertion/deletion modification |
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What is deamination? |
A --> I C --> U = removal of an amine group |
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What alters to change U --> Upsi |
addition of an extra H bond |
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Other form of base modification? |
methylation |
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General effects of mRNA editing? |
creation/removal/alertation of START/ STOP codons a.a and SPLICE SITE changes creation of new READING FRAME |
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What is the most prevalent modification in Euk. mRNA ? |
N6 - methyladenosine |
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what are methytransferases essential in? |
yeast flies zebra fish arabidopsis embryonic development |
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function of methyltransferases in mammals ? |
stem cell differentiation circadian rhythm cell cycle splicing..... |
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What is deaminated adenosine, Inosine the same as, according to translational machinery? |
Guanosine |
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What is ApoB ? |
protein involved in transport of lips around the body |
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Does ApoB mRNA editing in occur the liver or intestine ? |
Intestine |
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What enzyme is involved in ApoB editing? and what does it carry out? |
ApoBEC-1 enzyme C --> U = stop codon ApoB-100 --> ApoB-48 |
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Why does the intestine undergo editing? |
so its no longer able of LDL-receptor binding |
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Where are Glutamate Receptors subject to A --> I editing? |
at the Q/R site (GluR 2,5,6) |
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Which of Q (glutamine) and R (Arginine) is charged? |
R (+) |
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What is affected by editing? |
Change in charge affects function directly |
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What is the major excitatory neurotransmitter? |
L-Glutamate |
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What decreases upon editing? |
Ca2+ permeability of channels containing the 'R' version |
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What carries out this editing? |
Adenosine Deaminase acting on RNA ADAR2 |
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Mutations in ADAR2 gene lead to what symptoms? |
seizures, post-natal death, neurodegenertion in hippocampus |
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When does the RNA export from and to? |
Nucleus to Cytosol |
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How does it export? |
Through the nuclear pore; Active transport of larger molecules through impermeable membrane (long tails which are charged can form a gel which requires a push) |
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What provides a gradient across the nuclear membrane? |
GTPase RAN = GTP and GDP bound |
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What drives active transport? |
hydrolysis on RAN |
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Why localise mRNA? |
Protein Synthesis Generate cell polarity Prevent expression in the wrong place Efficient protein targeting Local translation control |
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Localisation mechanism of: Drosophila oocyte development |
RNA laid down at specific places of cell parts of cell --> different development e.g. RNAosk --> germ cells |
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Localisation mechanism of: Xenopus oocytes |
Asymmetric Several RNAs to one side --> polarity development RNA --> translocation --> gradient of proteins --> signals |
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Localisation mechanism of: Fibroblasts- migrating cells |
Polarised cell, ruffles at front edge Internal structure, actin, enables function mRNAs accumulate on front edge where proteins are then made |
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Localisation mechanism of: Dendritic Cells |
Trafficked up neurones Local translation --> generates many molecules for function |
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How does localisation occur by diffusion? |
nucleus --> molecules of cell surface which then trap them |
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How does localisation occur by active transport? |
nucleus export --> RNP remodelling -->RNP transport on cytoskeleton --> Anchoring on cell surface |
