That depends on what part of the body (or otherwise) you're talking about. Lots of the body's structure is made from extracellular protein. A common structural extracellular protein in humans is...
The most common protein that is used as a 'tag' for other proteins is GFP. In order to do this, the GFP gene sequence is simply added at the end of the gene sequence for the target protein. GFP is...
You can't. But consider... 1. ...that very few proteins are insoluble in their native context (that of a living organism), meaning that your attempts to mimic the conditions that the protein normally...