In the fat-shedding livers, by contrast, she found high concentrations of a protein called fatty-acid-binding-protein 4.

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PCBs do their damage by binding to a protein called the aryl hydrocarbon receptor, or AHR, thus stopping it working properly.

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And the trouble is, neither of the above approaches tells you much about any particular binding site that a protein may be looking for.

ECONOMIST: How (and why) to find a needle in a haystack | The

This second kind of analysis is done by lining up lots of known binding sites for a particular protein, comparing them position by position, and so finding out which letter is most likely to occur at which position, and how probable it is that a different letter may sometimes crop up instead.

ECONOMIST: How (and why) to find a needle in a haystack | The

And it allows Dr Schneider to pretend he is a protein looking for a binding site.

ECONOMIST: How (and why) to find a needle in a haystack | The

This binding process stimulates production of a protein called interleukin-10 (IL-10) that acts as an anti-inflammatory compound and which helps keep the immune system's response to the infection in check.

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For instance, is the binding site just a rare variant, or does it contain mutations that have reduced the information so much that the protein can no longer recognise it?

ECONOMIST: How (and why) to find a needle in a haystack | The