I am trying to find a technique where someone has successfully expressed and purified a protein complex (three different proteins) to then be used in x-ray crystalography.
However, you want to express your proteins for crystallography in bacteria unless you have a very rich aunt who likes you a lot. :D
seriously, make the protein in bacteria and reconstitute the complex in-vitro. You are interested in ~50-2000uM highly pure sample when trying to grow crystals.