Prions

[mee]

In mad cow disease, perhaps the prions cause the brains naturally similar proteins to change into the new form because the new form is somehow more efficient to reproduce than the other, natural form. Perhaps it could be the path of least resistance for the brain to produce the protein in the new form. I'm not sure if this will help cure it, but perhaps it could help determine the mechanisms for illness. Please feel free to forward this to anyone who might find this useful.

[Jikx]

From what I understand, Prions are actually the indentical protein (i.e same amino-acid sequence) but has a grossly different structure - prions cause normal protein to 'convert' into this form. As for efficiency.. I'm not sure, it is known however that prions are very stable. Resistant to heat treatment as well as enzymes..

I don't think we know whether prions can occur spontaneously, but it can be transmitted - as evidenced by vCJB (mad cow) scare a few years back.

[mee]

From what I understand, Prions are actually the indentical protein (i.e same amino-acid sequence) but has a grossly different structure - prions cause normal protein to 'convert' into this form. As for efficiency.. I'm not sure, it is known however that prions are very stable. Resistant to heat treatment as well as enzymes..

I don't think we know whether prions can occur spontaneously, but it can be transmitted - as evidenced by vCJB (mad cow) scare a few years back.

As to the mechanisms for conversions of the natual protein, is it an actual conversion by the one protein to another? Could we place a significant number of the natural protein in a petri dish by itself and add a prion and they would all convert or is it a cellular function which the prion affects that causes the change and no change without the cellular process? As to efficiency, the natural protein is most likely in the cell for a reason, i. e. it has a function. If the prion is more efficient at that function but causes side effects in the process, the cell would perhaps reproduce that which is most efficient? Just a theory, maybe others later.

[iansmith]

http://www.ninds.nih.gov/health_and_medical/pubs/creutzfeldt-jakob_disease_fact_sheet.htm

If you can get access to this paper it might answer some of your questions
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WSR-4CHYGBB-1&_coverDate=06%2F04%2F2004&_alid=191932984&_rdoc=1&_fmt=&_orig=search&_qd=1&_cdi=7053&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=181e804b3ac28d952e14cdc9dcb760f9

[Moonbear]

I think it's a good question to ask why we have the prion proteins in the first place. I don't have an answer to that. Are they required for normal functions, or are they a remnant of a viral protein inserted into our genome a long time ago in our evolutionary history? Certainly our approaches to eliminating the disease may differ depending on whether the normal protein is required for normal function, or if it is something extraneous we could simply do without.

It's not likely the mutant form would be the more energetically favored form, as it would then likely be the more naturally occurring form, unless there is something in our body that keeps it in check, and enzyme that continually converts it back to the "normal" form. My guess, and this is only a guess, is that the more likely explanation is that the mutant form, once it occurs, can catalyze the reaction of the normal form into more of the mutant form.

There was a news story that I just read (came out earlier this week, but I'm still catching up on missed news since I was away for the week) that indicated a woman was diagnosed with CJD on autopsy, but the disease was not present in her brain, but rather her spleen. I found this curious since CJD is typically associated with the central nervous system and transmission supposedly occurs through contact with tissues of the CNS, not peripheral organs. This woman apparently contracted the disease through a blood transfusion. To me, this suggests many more possibilities for human to human or animal to human transmission than have previously been recognized. While it still seems that animal to human transmission may be occurring, it seems to me that it's important to continue considering alternate routes of transmission among humans to ensure proper precautions are being taken to prevent further spread of the disease.