QUESTIONS: alpha-helix "signals" in proteins

[Mr Neville Steven Percy]

Loadsa people write:

[...] Loadsa stuff -- an excellent thread! -- [...]

BUT: Mark J. Dresser wrote:

>QUESTIONS:  What role do/could tertiary interactions play in stabilizing
>the alpha-helix?

Tertiaries are bound to play a strong role, and in fact quaternaries have 
been completely overlooked in this thread so far!

>Does a protein first fold into its secondary structure elements and then into its tertiary structure, afterwhich the original secondary structure elements
>remain as before the folding into the tertiary structure?  (If yes or no, could
>you please provide references).

Yes, this is correct, but it should further be pointed out that in the lumen of
the rough endoplasmic reticulum where all this folding of the nascent protein
chain is going on, there are a great quantity of chaperone molecules.
Chaperones serve to protect regions of secondary structure from the 
potentially damaging effect of exposure to the aqueous environment, until the 
entire protein has been synthesized and all the secondary structure elements 
can align to one another and form the final tertiary configuration, at which 
point the chaperone dis-associates, and leaves this to happen.

I imagine the kinetics of interaction with chaperones is therefore very 
important in vivo, if not in such in vitro systems as may be used for protein
structure studies... but this is very IMHO, as there are obviously a lot more
specialized people than myself contributing to this thread!   :)

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(Mad Cow Disease)       Neville Percy ;  spbcnsp at ucl.ac.uk          _.=~-.--=~
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