Biochemistry of the Splicing Reaction
In the first step of the splicing reaction the branch point nucleotide reacts with the 5’ splice site at the end of the first exon (exon1). Subsequently the last nucleotide of exon1 reacts with the first nucleotide of exon2 and thus forms a continuous nucleotide chain and the intron is released in the form of a lariat. The occurring reactions are formally transesterification reactions.
Scheme of the two transesterification reactions taking place in splicing.
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