What are the advantages of heterologous expression systems? I am doing research in a lab and I am relatively new to wet lab work. Many experiments that people are doing in my lab include overexpressing a protein of interest from another species (e.g. mouse) into CHO cells via transfection. I have learnt that these are examples of heterologous expression systems. I was wondering in general, what are the advantages of heterologous expression systems? I have read that you can use them to study the function of a protein in a well-defined, controllable environment. However, I was wondering what other benefits/uses are there to these kinds of experiments? Any insights are appreciated.

* It takes significant resources to establish a cell line. More efficient to use existing lines.

* Often cell lines used for expression grow faster. This is why so many proteins are expressed in E coli - they only take a day to grow vs the week or two for mammalian cells, meaning you get a much faster learning iteration in your research.