Question about quantitating western blots.

Warren Gallin wgallin at
Wed Dec 19 18:52:00 EST 2001

	Proportional means linear relationship,

	(amount of protein) = (some constant) X (signal intensity).

	Therefore, although there may be a range of intensity where there is
proportionality, there is no way to find that region a priori.

	What is true is that signal intensity is a monotonic function of the
amount of protein, where that function may be complex and vary between
experiments.  In that case, construction of a standard curve that spans
the values of signal intensity generated by the unknowns  allows for a
reasonably accurate interpolation.

	So the message is, to get a real measure of protein amount from a
Western blot you MUST run a standard curve that covers the range of the
unknown intensities.

Warren Gallin

Avi wrote:
> Ian A. York iayork at wrote in <9ur9ml$330$1 at>:
> >
> >You absolutely can not do this. (Well, you can *do* it, but the results
> >will be meaningless.)  The intensity of a band is not propertional to the
> >amount of protein in the band, on a western.  There are too many
> >non-linear processes involved.
> >
> >
> Huh? of course its proportional. One can definetly, within the same
> memmbrane, scan them, quantifie, and compare them, making the control 100%.
> If this cannot be done, and band intensity is not a mesurment of more or
> less protein, most papers published in the past 15 years should be
> disregarded!!
> unless i did not understand
> Avi

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