The phrase "master regulator" refers to something that controls or governs other things. It is an entity or factor that has significant control or influence over various processes or activities. Full definition
The regulators included proteins known as master regulator transcription factors. (sciencedaily.com)
Thus, Fanconi anaemia proteins are emerging as master regulators of genomic integrity that coordinate several repair processes. (science.institut-curie.org)
In 2003 Sinclair's lab published a paper in Nature that described the discovery of a gene that switched on in the yeast cell in response to calorie restriction, which Sinclair calls a «master regulator in aging.» (scientificamerican.com)