Hi guys,
A gene will be translated into a hnRNA fisrt. After processing like cutting the introns, hnRNA will become mRNA in eukaryocyte cell.
When we want to establish a plasmid carrying this gene, we use the mRNA of this gene as the template to build its corresponding cDNA and insert it into the plasmid. Then, the plasmid will be trasfected into eukaryocyte cell and express this gene.
The question is...how could this gene express the right protein in eukaryocyte cell? The cDNA (which is inversely transcripted from the mRNA of gene) will be translated into hnRNA first and processing a cutting of introns AGAIN (the introns has already been cut, but in cell's opinion, it's just a strain of hnRNA), resulting into a totally wrong protein expression.
Thank you!
The cDNA is normally not from the hnRNA but rather is from the final spliced mRNA. So there are no longer any introns present in the cDNA and no splicing will occur. So the only protein that will be made is the one encoded by that particular cDNA.
where did you get that idea?
Michael above is right.
If you have one already-spliced mRNA being made in the cell (what you are calling hnRNA) there are no splice sites any more. No intron to remove. Having cloned the cDNA, the hnRNA being made is exactly equivalent to the mature, spliced mRNA you want to make.
A difficulty presents itself if you know your gene (not mRNA) can produce alternatively spliced variants. In that case you must ensure that your clone contains the cDNA that encodes the isoform of the protein you wish to make.
Hi Yuanjian,
I agree with the comments above. The cDNA of the target protein in eukaryotic cells can definitely express the protein, and there is no need to consider the problem of introns.
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