I would like to use a glycine- serine linker to link a FLAG-tag to the N-terminus of a recombinant protein. I'm not sure which codons for glycine are optimum for expression in HEK-293t cells. Any advise would be very welcome.
There are a variety of codon optimization tools which can help you with this exact problem! I've used IDT's Codon Optimization Tool quite a bit to great success. You simply need to input your desired amino acid sequence and select expression organism, and the program will give you a recommended DNA sequence.