Is a prion ...

[Enigl]

In article <337A5809.6298D92E at utoronto.ca>, Martin Jugenburg
<martin.jugenburg at utoronto.ca> writes:

>
>Prion is a regular brain protein that just happens to be modified
>(glycosylated) in a unique manner. 

I've seen this error before.  It's time I said something to correct the
misconception, i.e. the _incorrect_ use of the word prion.  A prion is the
_abnormal_ form (PrPsc) NOT the normal form of the glycoprotein PrPc.  A
prion should not be confused with a "regular" brain protein PrPc.  The
prion is a lethal, pathological, infectious agent, protein.  

Theory:  A prion post-translationally combines with the normal protein
PrPc to form a heterodimer (PrPc/PrPsc) then to a homodimer (PrPsc/PrPsc).
 The gene for the normal protein is on chromosome 20.  The toxic form is
made before PrPc is sialyated within the Golgi apparatus and before entry
into lysosomes.  PrPsc accumulated in the vacuoles and secondary lysosomes
leading to cell death (highest concentration in the neurons).  

The function of the normal ( _NON-prion_ ) PrPc is unknown.  

Davin


Davin C. Enigl, MEAS (Master of Environmental Arts and Sciences), S.P.
President-Microbiologist

Microbiology Consulting,  Hazard Analysis and
Critical Control Points (HACCP), CGMP, and Validations
for the Food, Cosmetic, Nutritional  Supplement, and Pharmaceutical
Industry

enigl at aol.com
http://members.aol.com/enigl/index.html

May 15, 1997
8:05 am PACIFIC