Editing Protein production (section)

==== Eukaryotic systems ====

===== Yeasts =====
Expression systems using either ''[[Saccharomyces cerevisiae|S. cerevisiae]]'' or ''[[Pichia pastoris]]'' allow stable and lasting production of proteins that are processed similarly to mammalian cells, at high yield, in chemically defined media of proteins.<ref name="pmid11098467" /><ref name="pmid21943899" />

===== Filamentous fungi =====

Filamentous fungi, especially ''[[Aspergillus]]'' and ''[[Trichoderma]]'', have long been used to produce diverse [[industrial enzymes]] from their own genomes ("native", "homologous") and from recombinant DNA ("heterologous").<ref name="Visser 214–223" />

More recently, ''[[Myceliophthora thermophila]]'' C1 has been developed into an expression platform for screening and production of native and heterologous proteins.The expression system C1 shows a low viscosity morphology in submerged culture, enabling the use of complex growth and production media. C1 also does not "hyperglycosylate" heterologous proteins, as ''Aspergillus'' and ''Trichoderma'' tend to do.<ref name="Visser 214–223" />

===== ''Baculovirus''-infected cells =====
{{See also|BacMam}}
[[Baculoviridae|Baculovirus]]-infected insect cells<ref name="ReferenceA">{{cite journal | vauthors = Altmann F, Staudacher E, Wilson IB, März L | title = Insect cells as hosts for the expression of recombinant glycoproteins | journal = Glycoconjugate Journal | volume = 16 | issue = 2 | pages = 109–23 | date = February 1999 | pmid = 10612411 | doi = 10.1023/A:1026488408951 | s2cid = 34863069 }}</ref> ([[Sf9 (cells)|Sf9]], [[Sf21]], [[High Five cells|High Five]] strains) or mammalian cells<ref>{{cite journal | vauthors = Kost TA, Condreay JP | title = Recombinant baculoviruses as expression vectors for insect and mammalian cells | journal = Current Opinion in Biotechnology | volume = 10 | issue = 5 | pages = 428–33 | date = October 1999 | pmid = 10508635 | doi = 10.1016/S0958-1669(99)00005-1 }}</ref> ([[HeLa]], [[HEK 293 cells|HEK 293]]) allow production of glycosylated or membrane proteins that cannot be produced using fungal or bacterial systems.<ref name="ReferenceA"/><ref name="pmid15877075" /> It is useful for production of proteins in high quantity. Genes are not expressed continuously because infected host cells eventually lyse and die during each infection cycle.<ref>{{cite journal | vauthors = Yin J, Li G, Ren X, Herrler G | title = Select what you need: a comparative evaluation of the advantages and limitations of frequently used expression systems for foreign genes | journal = Journal of Biotechnology | volume = 127 | issue = 3 | pages = 335–47 | date = January 2007 | pmid = 16959350 | doi = 10.1016/j.jbiotec.2006.07.012 }}</ref>

===== Non-lytic insect cell expression =====
Non-lytic insect cell expression is an alternative to the lytic baculovirus expression system. In non-lytic expression, vectors are transiently or stably [[Transfection|transfected]] into the chromosomal DNA of insect cells for subsequent gene expression.<ref name=Dyring>{{cite journal | last1 = Dyring | first1 = Charlotte | year = 2011 | title = Optimising the drosophila S2 expression system for production of therapeutic vaccines | journal = BioProcessing Journal | volume = 10 | issue = 2| pages = 28–35 | doi=10.12665/j102.dyring}}</ref><ref name=Olczak>{{cite journal | vauthors = Olczak M, Olczak T | title = Comparison of different signal peptides for protein secretion in nonlytic insect cell system | journal = Analytical Biochemistry | volume = 359 | issue = 1 | pages = 45–53 | date = December 2006 | pmid = 17046707 | doi = 10.1016/j.ab.2006.09.003 }}</ref> This is followed by selection and screening of recombinant clones.<ref name=McCarroll>{{cite journal | vauthors = McCarroll L, King LA | title = Stable insect cell cultures for recombinant protein production | journal = Current Opinion in Biotechnology | volume = 8 | issue = 5 | pages = 590–4 | date = October 1997 | pmid = 9353223 | doi = 10.1016/s0958-1669(97)80034-1 }}</ref> The non-lytic system has been used to give higher protein yield and quicker expression of recombinant genes compared to baculovirus-infected cell expression.<ref name=Olczak /> Cell lines used for this system include: [[Sf9 (cells)|Sf9]], [[Sf21]] from ''[[Spodoptera frugiperda]]'' cells, [[High Five cells|Hi-5]] from ''[[Cabbage looper|Trichoplusia ni]]'' cells, and [[Schneider 2 cells]] and Schneider 3 cells from ''[[Drosophila melanogaster]]'' cells.<ref name=Dyring /><ref name=McCarroll /> With this system, cells do not lyse and several cultivation modes can be used.<ref name=Dyring /> Additionally, protein production runs are reproducible.<ref name=Dyring /><ref name=Olczak /> This system gives a homogeneous product.<ref name=Olczak /> A drawback of this system is the requirement of an additional screening step for selecting viable [[Clone (cell biology)|clones]].<ref name=McCarroll />

===== ''[[Excavata]]'' =====
''[[Leishmania]] tarentolae'' (cannot infect mammals) expression systems allow stable and lasting production of proteins at high yield, in chemically defined media. Produced proteins exhibit fully eukaryotic post-translational modifications, including [[glycosylation]] and disulfide bond formation.{{citation needed|date=August 2015}}

===== Mammalian systems =====
The most common mammalian expression systems are [[Chinese hamster|Chinese Hamster]] [[ovary]] (CHO) and Human embryonic kidney (HEK) cells.<ref name="Zhu 1158–1170">{{cite journal | vauthors = Zhu J | title = Mammalian cell protein expression for biopharmaceutical production | journal = Biotechnology Advances | volume = 30 | issue = 5 | pages = 1158–70 | date = 2012-09-01 | pmid = 21968146 | doi = 10.1016/j.biotechadv.2011.08.022 }}</ref><ref name=":0">{{cite journal | vauthors = Almo SC, Love JD | title = Better and faster: improvements and optimization for mammalian recombinant protein production | journal = Current Opinion in Structural Biology | volume = 26 | pages = 39–43 | date = June 2014 | pmid = 24721463 | pmc = 4766836 | doi = 10.1016/j.sbi.2014.03.006 | series = New constructs and expression of proteins / Sequences and topology }}</ref><ref>{{cite journal | vauthors = Hacker DL, Balasubramanian S | title = Recombinant protein production from stable mammalian cell lines and pools | journal = Current Opinion in Structural Biology | volume = 38 | pages = 129–36 | date = June 2016 | pmid = 27322762 | doi = 10.1016/j.sbi.2016.06.005 | series = New constructs and expression of proteins • Sequences and topology }}</ref>
* [[Chinese hamster ovary cell]]<ref name=":0" />
* [[Mouse]] myeloma [[Lymphoblast|lymphoblstoid]] (e.g. NS0 cell)<ref name="Zhu 1158–1170"/>
* Fully Human
** Human embryonic kidney cells ([[HEK 293 cells|HEK-293]])<ref name=":0" />
** Human embryonic retinal cells (Crucell's Per.C6)<ref name=":0" />
** Human [[amniocyte]] cells (Glycotope and CEVEC){{Cn|date=January 2024}}