Gating functions in protein networks

r norman rsnorman_ at _comcast.net
Thu Jul 24 03:33:31 EST 2003


On 15 Jul 2003 14:57:00 +0100, Lord Snooty <bonzo at dog.com> wrote:

>It seems clear that a Boolean AND function occurs in nature. Also, it is
>clear that, since both inhibition and excitation of pathways exists, we
>can have a NOT gate equivalent. But does an OR gate exist in natural
>protein pathways? An XOR gate?
>
>-Andrew

If you really insist on thinking in those terms, any situation where
alternative patheways exists might be considered 'OR'.  And it is
trivial to construct XOR from other functions
    (x AND NOT y) OR (NOT x  AND y)

Neural circuits have been known to have these properties since the
days of McCullough and Pitts, back a half a century ago.  Biochemical
systems similiarly can be made to do "logic".  In the intervening
decades, enormous strides have been made in understanding all sorts of
neural and biochemical events, but no in the context of boolean
algebra. Analyzing neural or biochemical pathways in this manner might
be interesting and have a certain theoretical elegance, but it doesn't
seem to be a useful way of looking at real biology.





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