Yes, but many proteins can be boiled down to basically two classes - the folded portion, and the unfolded portion. The folded portions are typically shared (shared is a loose term, there's a lot of leeway) among almost all proteins.
So, I can pull a protein out of thin air and there's a good chance it'll have an overall fold similar to another protein that's got a structure. Unfortunately, the devil is almost always in the details. An amino acid here or there, a short extension here or there, a missing charged residue or an extra glycine and now you have a different target and entirely different behavior in a biological system.
One cool thing I found actually, was a protein in an Archaeal virus had no known homology a few years ago, but when I checked the other day, it now matches most closely to an (otherwise thought to be) entirely synthetic protein out of David Baker's lab at UW. Which means this Archeal virus and David Baker converged on the same fold somehow (likely because it was "stable").
So, I can pull a protein out of thin air and there's a good chance it'll have an overall fold similar to another protein that's got a structure. Unfortunately, the devil is almost always in the details. An amino acid here or there, a short extension here or there, a missing charged residue or an extra glycine and now you have a different target and entirely different behavior in a biological system.
One cool thing I found actually, was a protein in an Archaeal virus had no known homology a few years ago, but when I checked the other day, it now matches most closely to an (otherwise thought to be) entirely synthetic protein out of David Baker's lab at UW. Which means this Archeal virus and David Baker converged on the same fold somehow (likely because it was "stable").