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Host cells
 

Comparison of commonly used host cells for protein expression

Host cells Advantages Disadvantages
E.coli High yield, 5% to 20% of total cellular proteins, some can reach 40%, up to 80% has been reported.
Inclusion bodies facilitate purification.
Large vector and fusion choices.
Easy operations, rapid growth rate, low cost.
Convenient expression control.		 Over-expression may be insoluble (inclusion bodies) and may not be refolded.
Lack post-translational modification.
Endotoxin.

 
Yeast No endotoxin or human pathogens, considered to be safe.
Well-developed large scale system.
Secretion facilitates purification.
Low cost fermentation.
disulfide bond formation and some glycosylation.

 		 Difficult to break cell wall for protein purification.
Less vector choices and more difficult vector manipulation than E.coli.
Less understanding of genetics and more difficult expression control than E.coli.
Different glycosylation than mammal.
Insect
(Baculovirus)		 Post-translational modifications similar to mammal.
Clinical trials approved by FDA using proteins produced by Baculovirus.
High yield facilitate protein purification.
 		 High mannose glycosylation and over-phosphorylation.
Recombinant proteins may not be 100% active.
Over-expression may result in insoluble inclusion bodies.
Mammal Recombinant protein activity same as natural protein.
Large scale mammalian cell culture feasible.


 		 Low cell growth rate, high cost.
Low yield, can compare with microbe yield in large scale.
Cell culture involves expensive labor, facilities, and consumables.

Protein expression using transgenic animals and cell-free systems are not included here. There is no single system meets all protein expression needs. Multiple systems may be chosen for an expression. However it also increases time, labor, and cost significantly.

Expression problems and host systems

Host cells

Difficult cloning

No or variable
expression

Low yield

Insoluble

Unstable

Dysfunctional

E.coli

 Detoxification media, cell strains, and vectors. tRNA supplement cell strains.
Detoxification media, cell strains, and vectors.		 Special media.
tRNA supplement cell strains.
Detoxification media, cell strains, and vectors.		 Special media.
Co- express with chaperones.
Lower temperature		 Special media.
Co- express with chaperones.		 Special media.
Co- express with chaperones.
 

Yeast

 E.coli is normally used for DNA cloning. May express because of different codon usage. Secretion may get good yield. Successful secretion should be soluble. No much help.
 		 Some glycosylation may not help much.

Insect
(Baculovirus)

 E.coli is normally used for DNA cloning. May express because of different codon usage. Baculovirus vector can have high yield. High yield may result in insoluble inclusion bodies. No much help.
 		 Glycosylation and phosphorylation may not be same as mammal.

Mammal

 E.coli is normally used for DNA cloning. May express because of different codon usage. Generally lower yield than other systems. Mostly soluble proteins. May be stable in right cell lines. May be functional because of right modifications.

Protein expression using transgenic animals and cell-free systems are not included here. There is no single system meets all needs of protein expression. Multiple systems may Protein expression using transgenic animals and cell-free systems are not included here. There is no single system meets all needs of protein expression. Multiple systems may be chosen for an expression. However it also increases time, labor, and cost significantly.

Your comments and suggestions are greatly appreciated at info@exptec.com.


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