Why Proteins? - Can't figure proteins out, let's find some help? (Aug/10/2008 )

I am new to a research lab and we're doing Western's. After a while of transfering proteins to a nitrocellulose membrane someone asked me why proteins? I didn't actually have a response and I read through my Doctor's papers and I still can't find a reason why. I know that they make for signaling on the membrane but I don't understand still 'why proteins?' Can someone help me out please?

You are trying to detect the machines that do the work in or make up the structure of the cell, thus you do a western blot looking for proteins. If you were trying to detect the blueprints of the machine, you'd do a Southern blot to detect DNA, or a northern blot to detect RNA.

As an aside, note that "Southern" is the only one of these blots properly capitalized, as Southern is a man's name (Edwin Southern, inventor of the blot procedure). The other blots use similar procedures to detect other molecules, and thus are named with humorous derivatives of Southern's name; they are not, however, proper nouns, and thus should not be capitalized.

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I wasn't seeing it in terms of proteins as the functional unit, merely as something on the paper that is being detected. But following central dogma it makes since, genes encode for proteins and they in turn are the active parts.