Synthetic genes or other synthetic DNA fragments have become much more accessible in the past years. They allow for a very flexible construct design, as one can decide freely on which tags, protease cleavage sites and/or localization signals to include. It also allows codon optimization and a high sequence accuracy, which can be helpful for areas that are difficult to PCR such as very GC-rich regions or highly repetitive regions. Many companies now also offer immediate subcloning into a variety of expression vectors.