There's a lot we don't know about prions and a heck of a lot I don't know, but I would be surprised if prions turned out to be something substantially different from a misfolded protein.

I've never heard of prions targeting certain tissues. I need to do some reading, as it's been a while since my last bio course. Do you have an article that explains how that works? In order to have that ability, they would have to be more complicated than I understand them to be.