Biology Forums - Study Force

what is         exon shuffling       and        what are the mechanisms of exon shuffling?   :)

Exon shuffling is when genes that code for more then one protein exchange domains, coding for new multi-domain proteins.

For example, We have 3 sentences.

1) The dog went to the store.
2) I told him to stay at home.
3) The weather is nice,however.

I can switch the order of these sentences into 2 3 1,or 1 2 3, or 3 2 1,etc.

Exon shuffling is a molecular mechanism for the formation of new genes. It is a process through which two or more exons from different genes can be brought together ectopically, or the same exon can be duplicated, to create a new exon-intron structure.

There are different mechanisms through which exon shuffling occurs: transposon mediated exon shuffling, crossover during sexual recombination of parental genomes and illegitimate recombination.

Exon shuffling follows certain splice frame rules. Introns can interrupt the reading frame of a gene by inserting a sequence between two consecutive codons (phase 0 introns), between the first and second nucleotide of a codon (phase 1 introns), or between the second and third nucleotide of a codon (phase 2 introns). Additionally exons can be classified into nine different groups based on the phase of the flanking introns (symmetrical: 0-0, 1-1, 2-2 and asymmetrical: 0-1, 0-2, 1-0, 1-2, etc.) Symmetric exons are the only ones that can be inserted into introns, undergo duplication, or be deleted without changing the reading frame.

so, it has 3   (Crossover during sexual recombination of parental genomes/Transposon mediated/Illegitimate recombination) mechanisms or 2 mechanisms (Crossover / Transposon mediated) ???????????