It was a brilliant illustration of what the biologist and Nobel laureate François Jacob called the “logic of life”: a tightly controlled flow of information from genes to the traits that cells and other organisms exhibit.
But this lucid vision of circuit-like logic, which worked so elegantly in bacteria, too often fails in more complex cells. “In bacteria, single proteins regulate things,” said Angela DePace, a systems biologist at Harvard Medical School. “But in more complex organisms, you get many proteins involved in a more analog fashion.”
The evidence that interactions of proteins, RNA molecules and DNA genomic sequences involved in cell regulation are flexible and promiscuous has become ever more prevalent in the past decade or so. They turn up in a wide range of systems throughout biology. “Given that promiscuity did not have to exist, but is ubiquitous, the simplest and most reasonable assumption is that it is providing some functional capability,” Elowitz said.