Editing Recombinant DNA (section)

==DNA expression==
{{main|Protein production}}
DNA expression requires the transfection of suitable host cells. Typically, either bacterial, yeast, insect, or mammalian cells (such as [[HEK 293 cells|Human Embryonic Kidney cells]] or [[Chinese hamster ovary cell|CHO cells]]) are used as host cells.<ref>{{Cite news |last=Eberle |first=Christian |date=December 2022 |title=Recombinant DNA technology – Steps, Methods & Examples |newspaper=Evitria - |url=https://www.evitria.com/journal/recombinant-antibodies/recombinant-dna-technology/ |access-date=July 18, 2023}}</ref>

Following transplantation into the host organism, the foreign DNA contained within the recombinant DNA construct may or may not be [[Gene expression|expressed]]. That is, the DNA may simply be replicated without expression, or it may be [[Transcription (genetics)|transcribed]] and [[Translation (biology)|translated]] and a recombinant protein is produced. Generally speaking, expression of a foreign gene requires restructuring the gene to include sequences that are required for producing an [[mRNA]] molecule that can be used by the host's [[Translation (biology)|translational apparatus]] (e.g. [[Promoter (biology)|promoter]], [[Shine-Dalgarno sequence|translational initiation signal]], and [[Terminator (genetics)|transcriptional terminator]]).<ref name="pmid9487731">{{Cite journal
| last1 = Hannig | first1 = G.
| last2 = Makrides | first2 = S.
| title = Strategies for optimizing heterologous protein expression in Escherichia coli
| journal = Trends in Biotechnology
| volume = 16
| issue = 2
| pages = 54–60
| year = 1998
| pmid = 9487731
 | doi=10.1016/S0167-7799(97)01155-4
}}</ref> Specific changes to the host organism may be made to improve expression of the ectopic gene. In addition, changes may be needed to the coding sequences as well, to optimize translation, make the protein soluble, direct the recombinant protein to the proper cellular or extracellular location, and stabilize the protein from degradation.<ref>{{cite journal |last1=Mahmoudi Gomari |first1=Mohammad |last2=Saraygord-Afshari |first2=Neda |last3=Farsimadan |first3=Marziye |last4=Rostami |first4=Neda |last5=Aghamiri |first5=Shahin |last6=Farajollahia |first6=Mohammad M. |title=Opportunities and challenges of the tag-assisted protein purification techniques: Applications in the pharmaceutical industry |journal=Biotechnology Advances |date=1 December 2020 |volume=45 |page=107653 |doi=10.1016/j.biotechadv.2020.107653 |pmid=33157154 }}</ref><ref name="pmid|19892171">{{Cite book
 | last1 = Brondyk | first1 = W. H.
 | title = Guide to Protein Purification |edition=2nd
 | doi = 10.1016/S0076-6879(09)63011-1
 | chapter = Chapter 11 Selecting an Appropriate Method for Expressing a Recombinant Protein
 | volume = 463
 | pages = 131–147
 | year = 2009
 | pmid = 19892171
 | series = Methods in Enzymology
 | isbn = 978-0-12-374536-1
 }}</ref><ref>{{cite journal |last1=Ortega |first1=Claudia |last2=Prieto |first2=Daniel |last3=Abreu |first3=Cecilia |last4=Oppezzo |first4=Pablo Javier |last5=Correa |first5=Agustin |title=Multi-compartment and multi-host vector suite for recombinant protein expression and purification. |journal=Frontiers in Microbiology |date=2018 |volume=9 |pages=1384 |doi=10.3389/fmicb.2018.01384 |pmid=29997597 |pmc=6030378 |doi-access=free }}</ref>