Figure 2. Buffering and potentiating interactions are prevalent within gene-regulatory networks.

Very simple molecular interactions result in buffering and potentiation. (A) A repressor can mask the phenotypic effects of mutations in its target. Shown here, a mutation in gene b, marked with an asterisk, would act to increase cell size, but this effect is buffered by gene a, which encodes a repressor of gene b’s expression. Loss of function of gene a (red) abrogates buffering. (B) An activator can enhance the phenotypic effects of mutations in its target. Shown here again is a mutation in gene b that increases cell size, but this time the effect is potentiated by gene a, which here encodes an activator of gene b’s expression. Loss of function of gene a (red) abrogates potentiation. Throughout the figure, green color indicates regulatory interactions that underlie buffering or formerly buffered traits; purple color indicates regulatory interactions that underlie potentiation or potentiated traits; and gray color indicates regulatory interactions that do not exist or genes that are not expressed in the particular scenario.