Summary: Splicing of precursor mRNA (pre-mRNA) is a crucial
regulatory stage in the pathway of gene expression:
introns are removed and exons are ligated to form
mRNA. The inclusion of different exons in mRNA --
alternative splicing (AS) -- results in the generation of
different isoforms from a single gene and is the basis
for the discrepancy between the estimated 24,000
protein-coding genes in the human genome and the
100,000 different proteins that are postulated to be
synthesized1
. Splicing in general, and AS in particular,
is also important for regulation of the levels and tissue
specificity of gene expression and, if disrupted, can lead
to disease2­5
.
The importance of splicing is emphasized by its
presence in species throughout the phylogenetic tree.
However, we still have much to learn about how diverse
intron­exon structures are generated and recognized.
Comparing species to see what has changed and what is

Source: Ast, Gil - Department of Molecular Genetics and Biochemistry, Tel Aviv University

Collections: Biology and Medicine