Codon optimization is intended to maximize expression of a protein by avoiding the use of rare codons during translation. Therefore, you should optimize the codons for expression in whatever organism you plan to use. If you want the protein to be properly glycosylated, you should express it in the same organism from which it originates, if possible.

Dear Shapiro,

Does high expression level will effect protein glycosylation and folding in this case "highly glycosylated protein"? is there proper translational pause has some importantce in folding?

In heterologus expression system , protein is still also functional.

Thanks,

Best Wishes.

These are very good questions. They presume that you are expressing the protein in a homologous expression system. You could try comparing the proteins expressed from native and codon-optimized sequences to see which expresses better. Do you have a way to compare the glycosylation of the overexpressed protein to the native protein's glycosylation?