  There is increasing evidence that protein binding to specific sites along DNA
can activate the reading out of genetic information without coming into direct
physical contact with the gene. There also is evidence that these distant but
interacting sites are embedded in a liquid droplet of proteins which condenses
out of the surrounding solution. We argue that droplet-mediated interactions
can account for crucial features of gene regulation only if the droplet is
poised at a non-generic point in its phase diagram. We explore a minimal model
that embodies this idea, show that this model has a natural mechanism for
self-tuning, and suggest direct experimental tests.
