Table 1.

Comparison of Recombinant Protein Expression Systems

	E. coli	Yeast	Insect cells	Mammalian cells	Cell‐freea ( E. coli )	Cell‐freea (wheat germ)
Average time of cell division	30 min	90 min	18 hr	24 hr	N/A	N/A
Cost of expression	Low	Low	High	High	High	High
Expression level	High	Low‐High	Low‐High	Low‐Moderate	Low‐High	Low‐High
Success rate (% soluble)	40‐60	50‐70	50‐70	80‐95	Variable	Variable
Advantages	Simple, low cost, rapid, robust, high yield, easy labeling for structural studies	Simple, low cost	Post‐translational modifications	Natural protein configuration, post‐translational modifications	High yield, fast, flexible, disulfide‐bonded and membrane proteins, easy labeling for structural studies	Fast, flexible, disulfide‐bonded and membrane proteins, post‐translational modifications
Disadvantages	No post‐translational modifications, insoluble protein, production of disulfide‐bonded and membrane proteins is difficult	Less post‐translational modifications, production of membrane proteins is difficult	Slow, higher cost, production of membrane proteins is difficult	Slow, high cost, lower yield	High cost, less post‐translational modifications, efficient production requires highly‐specialized setup	High cost, lower yield than E. coli cell‐free system, efficient production requires highly specialized setup

^aSpirin, 2004; Langlais et al., 2007; for other references, see text.

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