What is the evolutionary advantage of splicing?
This has several advantages: (i) it allows a high sequence flexibility of exonic regulatory sequences that puts no constrains on coding requirements, (ii) the protein interaction can be influenced by small changes in the concentration of regulatory proteins which allows the alternative usage of exons depending on a …
What is a spliceosome and why are they important?
Spliceosomes are multimegadalton RNA–protein complexes responsible for the faithful removal of noncoding segments (introns) from pre-messenger RNAs (pre-mRNAs), a process critical for the maturation of eukaryotic mRNAs for subsequent translation by the ribosome.
How do introns evolve?
Firstly, there is growing evidence that spliceosomal introns evolved from group II self-splicing introns which are present, usually, in small numbers, in many bacteria, and probably, moved into the evolving eukaryotic genome from the α-proteobacterial progenitor of the mitochondria.
What role does the spliceosome play?
What is the evolutionary significance of alternative RNA splicing?
As important as the DNA code is, the alternative RNA splicing is equally, or more, important. In fact, recent research shows that alternative splicing may be the critical source of evolutionary changes differentiating primates and humans from other creatures such as worms and flies with a similar number of genes.
What snRNPs can you find in an active spliceosome?
Each spliceosome is composed of five small nuclear RNAs (snRNA) and a range of associated protein factors. When these small RNAs are combined with the protein factors, they make RNA-protein complexes called snRNPs (small nuclear ribonucleoproteins, pronounced “snurps”).
What do Spliceosomes act on and produce?
Spliceosomes are huge, multimegadalton ribonucleoprotein (RNP) complexes found in eukaryotic nuclei. They assemble on RNA polymerase II transcripts from which they excise RNA sequences called introns and splice together the flanking sequences called exons.
Why are there no introns in prokaryotes?
Over time, introns were lost from prokaryotes as a way to make proteins more efficiently. The mixing and matching of exons from the same gene can lead to proteins with different functions. Eukaryotes might need this diversity in proteins because they have many types of cells all with the same set of genes.