ELI5: What Are Prions?
Comments
gus_massa
pcthrowaway
Perhaps someone smart here can answer me this: Is there any chance whatsoever that lab-grown meat tech could somehow result in products which are more likely to cause prion diseases than regular meat?
I ask this as a vegan who would absolutely eat lab-grown meat if given the option, except for this one concern.
Perhaps lab-grown fish, poultry, and eggs (if those are a thing) would be safer than other types of lab-grown meat?
rcxdude
I doubt it, in fact it will likely be safer. One important thing about prions is there's basically only one protein that does it*, and it's only really produced in the brain. So lab-grown meat with no brain involved is less likely to have prions. You can even genetically engineer organisms to not have the protein, though it does seem to cause learning difficulties (hasn't stopped an attempt with farmed cows). Lab-grown meat could much more easily include that as well.
*There's another brain-degeneration disease thought to be caused by a prion behaviour in a slightly different protein, but it's not confirmed and it doesn't change the main point. You may also ask why there are so many different prion diseases, and they've basically due to slight differences in this protein between species as well as different mutations which can cause it to occur spontaneously (like Fatal Familial Insomnia).
pcthrowaway
> as well as different mutations which can cause it to occur spontaneously
Isn't it possible (or perhaps even more likely) that the tech used for culturing meat could result in more mutations though? Like, how are the people working on this controlling for unmutated proteins?
rcxdude
Even if so, it's mutations in a protein that isn't made in muscle tissue. You'd also need mutations which cause it to be made, which would likely involve it becoming not-muscle.
kosievdmerwe
I'm of the opinion that prions occur more often than we know, it's just that to be a prion "disease", you need more properties than just spreading the misfolded shape.
Importantly a critical property is that it needs to be damaging enough to be noticeable and neural matter has the unfortunate property that it heals slowly (if at all) so low level damage can accummulate.
rcxdude
Maybe, but even proving there's a second protein that does this in mammals would be a major discovery.
pcdoodle
That was a fun read. Excited to hear what HN has to add.
Most of the comment is correct, but
> Or maybe we could test how the proteins in the sample chemically react.
> ... but that doesn't help, because the atoms are connected the same way.
When the shape of a protein changes, the chemical reactions may change too. For example some proteins usualy bind to a specific molecule, but if you twist it incorrectly the "hole" where the molecule binds is broken. So it's theoreticaly possible to check this, but I don't know if it's easy in a lab.
> The only difference is in how the proteins are twisted...
> ... and we can't even figure out how proteins are supposed to be twisted in the first place,
In many important proteins we know.
> let alone how they're twisted in a specific sample.
From a sample there are sote techniques like x-ray difraction, but you need very pure samples, and be lucky that the protein forma a nice crystal, and perhaps a lot of other problems. We have done these in the past to determine the proteins shape before computers, but I think it's just too difficult with a small sample of human tissue.