Biochemistry and Molecular Biology II – Lecture 6: Posttranscriptional gene
control and nuclear transport #2 – Lecture by Ger Pruijn
08-05-2018
Nuclear speckles: areas with the highest concentration of splicing factors.
There are two types of enhancers:
1. On DNA-level
2. On RNA-level (exon-junction complex)
Alternative splicing: splicing more up- or downstream as normally (3’ or 5’ end)
Alternative splicing can result in many mRNAs from a single gene and can be
regulated in a tissue-specific manner.
Alternative splicing is regulated by RNA-binding proteins (Rbp’s).
Risks of alternative splicing:
- Frameshift can occur, leading to other genes and thus proteins.
- Complete exons can be skipped.
Depending on the position of the start codon, 5’ end splicing can affect the protein to
be synthesized (or not).
Alternative polyadenylation: does not affect the protein to be synthesized, because
the stop-codon lies in front (upstream) of the poly(A)-site.
Not all alternatively processed mRNAs are functional (NMD).
, There are many important consequences of alternative splicing, e.g. sexual
differentiation in Drosophila – determining the gender:
Skipping exon 3 female Drosophila.
Including exon 3 male Drosophila.
*The red line in exon 3 is caused by a nonsense mutation, leading to a premature
stop-codon causing the resulting protein to be abnormally shortened.
control and nuclear transport #2 – Lecture by Ger Pruijn
08-05-2018
Nuclear speckles: areas with the highest concentration of splicing factors.
There are two types of enhancers:
1. On DNA-level
2. On RNA-level (exon-junction complex)
Alternative splicing: splicing more up- or downstream as normally (3’ or 5’ end)
Alternative splicing can result in many mRNAs from a single gene and can be
regulated in a tissue-specific manner.
Alternative splicing is regulated by RNA-binding proteins (Rbp’s).
Risks of alternative splicing:
- Frameshift can occur, leading to other genes and thus proteins.
- Complete exons can be skipped.
Depending on the position of the start codon, 5’ end splicing can affect the protein to
be synthesized (or not).
Alternative polyadenylation: does not affect the protein to be synthesized, because
the stop-codon lies in front (upstream) of the poly(A)-site.
Not all alternatively processed mRNAs are functional (NMD).
, There are many important consequences of alternative splicing, e.g. sexual
differentiation in Drosophila – determining the gender:
Skipping exon 3 female Drosophila.
Including exon 3 male Drosophila.
*The red line in exon 3 is caused by a nonsense mutation, leading to a premature
stop-codon causing the resulting protein to be abnormally shortened.
