What the hell is a prion?

[Anarchaus]

im just wondering about this mystery molocule.

[Dak]

a prion is a protien. the differense between the prion form of a protien and the normal form of the same protien is in the way the protien is folded, which can have a huge effect on the charechtoristics of the protien. the other thing that makes a prion a prion, is that by putting normally-folded or unfolded protiens near the prion, they will bind to the prion and match its shape: so if you put a prion protien next to a normal form of the protien, the normally-folded proton will change shape and become a prion.

 

because of this ability to replicate, as it were, prions can cause disease; as in mad cow disease. the prion in this case is a misfolded form of a protien found in the brain. if a prion finds its way into the brain, then lots of the endogenouse protiens will become incorrectly folded, and will lose their function.

[Flareon]

Facinating. How exactly does it induce the other brain proteins to follow its suit and fold? Can you be so kind as to direct me to an on-line source, if you know of one?

[Dak]

sorry, im jus doing this from memory, but i immagine that if you google it...

 

i believe it induses the fold by eletromagnetic attraction, same as an enzymic indused fit, but by adopting the prion conformation parts of the protien are forsed into close proximity and react with each other to streangthen the shape (eg, systines being forsed together and forming sulphur bridges) so that when it dissociates from the original prion, it retains the prion shape.

[Diatom]

So are prions considered life? Since they can self-replicate.

[Flareon]

So are prions considered life? Since they can self-replicate.

 

Not necessarily. Many things--including modern machines and programs--can replicate themselves and not be considered "life." If we wish to discuss exactly what constitutes 'life,' then we can either search for or start another thread.

[Dak]

So are prions considered life? Since they can self-replicate.

no. theyre metabolically inert, for a start, ie dont eat, respire, excrete etc.

[Diatom]

no. theyre metabolically inert, for a start, ie dont eat, respire, excrete etc.

 

Wouldn't their metabolism include the protiens that they reform into other prions?

[Dak]

metabolism is breaking stuff down and building stuff up, with accompanied energy changes. i dont think that one single molecule can have a metabolism as such, even if, for example, it plays a role in the metabolism of an organism. for example, citrate isomerase plays a role in the kreb cycle of eukaryotes, however citrate isomerase doess not itself have a metabolism.

[hyebeh]

the way prions are formed and how the cause brain proteins to fold in a similar way is unknown. If you find out, you could win a noble prize. It's been a big puzzler for a while now.