[archgoon]

You do not 3D-print protein structures (unless you mean 3D models of proteins in which case ignore the rest of this post). Not in the sense of "here's an arbitrary position of atoms, give me a molecule". There's a reason why Folding@Home takes a lot of processing power. It's very hard to figure out how chains of amino acids will interact with themselves.

The best you can do is do gene synthesis using a method called Oligonucleotide Synthesis

http://en.wikipedia.org/wiki/Oligonucleotide_synthesis

Using this technique, you can take an arbitrary gene sequence (ATGC sequence) and get a plasmid out of it. This will specify a sequence of amino acids that will fold into a protein. Then you just have to get a bacterial host to take it up into it's DNA and then make sure the chemical conditions of the host are right to generate your protein (you can't synthesize a protein if there aren't the right types of Amino Acids floating around, for example).

Companies like Genscript (which I found by randomly googling) will manufacture a specified gene, and send you back frozen plasmids, which you can then inject into your favorite bacterial host.

http://www.genscript.com/gene_synthesis.html

[jamessb]

Depending on what exactly you want, you may be able to use a cell free translation system rather than transfecting a bacterial host (or yeast, or whatevever else).

Short peptides can also be produced by solid-phase synthesis: there are automated machines (peptide synthesisers) that produce a peptide with any arbitrary sequence from the constituent amino acids.

[car]

Thanks for the reply, but of course this question was in the context of the parent.

Just fyi, mammalian genes are usually expressed in mammalian cells, not bacteria, because of posttranslational modification.

[michaelbuddy]

"will manufacture a specified gene, and send you back frozen plasmids, which you can then inject into your favorite bacterial host."

As a fan of the Bioshock series, I wasn't sure if you were trolling here or I'm just completely unaware of the current state of real biology.

[archgoon]

Not trolling! Honest!

http://en.wikipedia.org/wiki/Plasmid#Vectors