Different promoters work better for different proteins. Expression of three proteins,
phi29 (~61 kD), cutinase (~22 kD) and DasherGFP (~26 kD), under control of different
promoters, T5 and T7 (IPTG-inducible), rham (rhamnose-inducible) and phoA
(inducible by phosphate starvation) is shown on an SDS-PAGE gel.
Case Study: Solubility Tag Panel Results
Soluble protein expression using different solubility tags is protein dependent. Three proteins
encoded by genes A (~48 kD), B (~49 kD) and C (~59 kD) with solubility problems were expressed in
E.coli expression vectors (pD441-XXX) with various N-terminal solubility tags MBP (~42 kD),
GST (~26 kD), PpiBT (~19 kD), Fh8 (~8.8 kD) and 6XHis as a negative control (~1 kD) under control of
the IPTG-inducible T5 promoter, at 37°C and room temperature (RT). Higher soluble protein expression
was observed at RT except for gene A with MBP tag. BL21 cells were transformed and grown at 37°C in
2 ml LB + 30 µg/ml kanamycin to an OD600 of 0.8. Cultures were induced by addition of 1mM IPTG and
incubated for 3 hrs at 37°C or overnight at room temperature (RT); uninduced cultures were run as
negative controls. Samples were pelleted, lysed and total and soluble preps prepared. Total protein
(T) samples and soluble fractions (S) were denatured and reduced in sample buffer with reducing agent
at 95°C for 10min. 5µl (approx. 5 O.Ds) of denatured sample was loaded per lane of a 4-12%
NuPAGE Bis-Tris MES gel and Coomasie stained. Band volumes (shown in red boxes) were measured and
quantitated using BSA as a reference.
Case Study: Secretion Signal Panel Results
Periplasmic expression of Cutinase from rhamnose vectors (pD881, low copy) with different secretion signals.
Total protein samples and periplasmic fractions were prepared and loaded on a 4-12% NuPAGE Bis-Tris
MES gel and Coomasie stained. As observed from the gels, there are clear differences in expression and
processing of the cutinase protein with different secretion signals seen in the periplasmic fractions (shown by arrows).
ATUM Expression Data Report
SDS-PAGE results for total and soluble protein fractions
Semi-quantitative Western* results (optional for genes with His or Flag tag)
Growth and induction protocols
Terms & Conditions
Expression panel tests are available for bacterial vector panels with a volume discount. Cost
for expression testing is $395.00 USD per construct per vector with a 10% discount off the total
testing cost. Discount does not apply to regular gene synthesis or cloning fees.
Prices are per construct (gene) and are in addition to regular gene synthesis and cloning fees.
* There is an additional $50 USD fee per gene for Western Blot service.
Listed prices are for genes <3kb in length. Please consult with our Expression Specialists to
determine specific pricing for genes longer than 3kb.
Expression Test services must be placed at time of order for each gene.
Expression Standard is >5µg/ml E. coli culture under standard conditions (5.0 OD600
culture in our expression conditions) in the ATUM laboratory (detectable via SDS-PAGE and/or Western).
ATUM will provide electronic gel image and protocols for expression to the customer.
ATUM does not guarantee protein solubility.
ATUM does not guarantee the ability of customers, researchers or external labs to produce similar expression levels.
ATUM reserves the right to decline Expression Test orders.
Have a question? Let's talk.
ATUM customer support scientists are available to discuss cloning strategies,
gene design constraints, bioinformatics analyses, and other molecular