Spliceosome Flashcards
When were intron discovered?
1970s
What are introns
Interveneing sequences
What are exons
Expressed sequences/Coding sequences
What does splicing require a lot of?
Hydrolysis of a large quantity of ATP
What does snRNPs stand for?
Small nuclar RiboNucleoProtein
Give an example of another cellular RNP
The ribosomal subunits
Where does the biogenisis of spliceosomal snRNPs take place?
In distinct subcellular compartments
Define the biogenisis of spliceosomal snRNPs
the assembly of stable, but inactive, pre-RNPs that require maturation at locations that are distinct from their sites of function
Define the biogenisis of spliceosomal snRNPs
the assembly of stable, but inactive, pre-RNPs that require maturation at locations that are distinct from their sites of function
What are ribonucleoprotein?
a complex of ribonucleic acid and RNA-binding protein
What is ribonucleic acid
RNA, a polymeric moleucle using the nitrogenous bases of guanine, uracil, adenine, and cytosine, denoted by the letters G, U, A, and C
What are snRNAs?
abundant, non-coding, non-polyadenylated transcripts
Where do snRNAs carry out their function?
Nuceloplasm
What is the nuceloplasm?
the type of protoplasm that makes up the cell nucleus, the most prominent organelle of the eukaryotic cell. It is enclosed by the nuclear envelope, also known as the nuclear membrane
What two basises are snRNAs be divided into?
Common sequence features and protein cofactors
What are the two major classes of snRNAs?
Sm and Sm-like
What are the seven Sm class of spliceosomal snRNAs?
U1, U2, U4, U4atac, U5, U11 and U12
What are the two Sm-like snRNAs?
U6 and U6atac
Why is are the classes called Sm?
They contain the Sm motif
What does the Sm motif composed of?
two conserved regions, termed Sm1 and Sm2, which are separated by a non-conserved linker region
What is a common feature of snRNA genes and protein-coding genes?
They both have elements that control transcriptin and RNA processing in the same relative position
Is the transcription and processing of snRNA the same as mRNA?
No, they are coupled by a cellular system that is parallel to but distinct from each other
What promotors are Sm class snRNAs transcribed from?
RNA polymerase II (pol II)
What do pol II promotors contain?
proximal and distal sequence elements similar to the TATA box and enhancer sequences, respectively, of protein-coding genes
What does the initiation of transcription of snRNA require?
binding of a pentameric factor called the snRNA-activating protein complex (SNAPc)
What is required for the maturation of the snRNA 3’ end?
a large, multi-subunit factor called the Integrator complex
Have they found an answer to pol II snRNA gene transcription termination?
No
Where do Sm class snRNPs primarily function?
In the nucleus
Why might precurson snRNPs undergo remodelling outside the place where they function?
This might be a mechanism for quality control, ensuring that partially assembled RNPs would not come into contact with their substrates.
Give examples of five RNAs
rRNA, tRNA, mRNA, miRNA and SRP RNA
How do appropriate transport receptors bind to RNAs?
They recognize specifc sequences and/or strutures on the RNA
