There are a few things GenScript scientists will do to solve the problem:
(1) codon optimization is recommended if it has not been;
(2) remove the transmembrane region and signal peptide region;
(3) try to express truncated domains of the protein;
(4) we can also try different tags to increase the expression level;
(5) we may recommend customer to try different expression systems (e.g. insect cell system for certain proteins).
For the Guaranteed/Advanced Package (SC1253), if the protein cannot be expressed and purified, we'll not charge anything but the gene synthesis fee. For other protein service packages, the fees will be charged for performed experiments. In all cases, expression evaluation report will be delivered.