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22 Cards in this Set
- Front
- Back
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4 things that are processed in pre-mRNA
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5' cap, 3' polyA, splicing, co-transcriptional processing
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Functions of 5' Cap
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protection, export, translational help
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3 properties of cap
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1.m7g:methylguanosine
2. 5'5' triphosphate linkage 3. 2-methyl ribose on first 2 rna's |
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What are 2 signals for polyA addition?
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AAUAAA and G/U sequences
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What happens in 3' cleavage?
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1. protein factors bind polyA signals
2. cleavage at polyA site 3. PAP adds A's to create polyA tail |
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3 spliceosome components
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1. protein
2. pre-mRNA 3. snRNA's |
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What kind of reaction happens in splicing?
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2 transesterification reactions
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What splice signals are recognized at the 5' splice site?
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GU, u1 binds here
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What is recognized at the 3' splice site and neighboring regions,
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AG, pyrimidine rich region, branch point A
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Where does u2 bind?
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branch point A
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what's a snRNP?
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snRNA's with proteins
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What do you call it when RNA pairs with itself?
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hairpins, stem loops, bulges
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What are all the steps in Splicing?
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1. u1 and u2 rna's assosciate with pre-MmRNA and then u4/5/6 join
2. rearragement activates the spliceosome 3. first transesterification rxn: branch A forms 2'5 bond with the 5' end intron 4. second transesterification: join exons, release intron 5. intron lariat linearized and degraded |
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What are SR proteins?
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assist in splicing, find the exon splice enhancer sequences and help spliceosome bind to correct splice sites
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how do SR proteins work?
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assist by binding to exon splice enhancers
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What's the CTD and what does it associate with?
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It's on RNA pol II , TFIIH, and it's a bunch of repeats that recruit factors that splice, 5'cap, and polyA
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How do cells regulate inclusion of exclusion of exons?
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Depends on the types of proteins that are availible, there are splicing repressors, and splicing activators
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3 things about the sxl gene
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1. early deveolopment SXL is made in female only
2. later, the sxl pre-mRNA is made in both 3. SXL binds intron between exons 2 and 3 to repress inclusion of exon 3, (3 has early stop codon) |
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what is tra? how is it produced?
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transformer gene, produced only in females, inhibited by sxl protein
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what is dsx? how is it spliced?
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tra recruits SR proteins to bind to exon 4, making female version. Males since they don't have tra will make 3,5
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How are mRNA's transported?
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. exporter proteins bind mRNA
• exporter proteins bind mature mRNA. mRNP (mribonuclearprotein) 2. mRNP interacts with NPC proteins to move through pore. Usually 5’ cap goes into cytoplasm first. 3. any of the transfer proteins release the mRNA in the cytoplasm and then go back into the nuclear. |
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what's an NPC?
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nuclear pore complex, boundary between the cytoplasm and nucelus
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