[tooiii]

 I want to do an analysis with crystallization on a trimeric protein complex. This trimeric protein complex is from mammalian tissue. Can I express and purify this protein from mammalian tissue culture cells?

[Borek]

Completely out of my area of expertise, but what other sources are possible?

[rolnor]

It's more microbiology than chemistry... But don't people insert a gene into e-coli and express proteins this way? Do you want to use x-ray diffraction? Now it's common to use AI that looks at the primary structure and predicts the tertiary 3D-structure. Before when people used only x-ray diffraction it often took years to get good crystals from proteins, at Medivir we got crystals from HIV-reverse transcriptase and used x-ray diffraction. The x-rays were generated by an electron accelerator large as a football field and the crystals were cooled by ice the whole transport to the facility, it was not a simple job.
I don't find the paper, but this guy did the work I describe, here he is also working with HIV-RT: https://www.liebertpub.com/doi/abs/10.1089/aid.1990.6.1297