 Aux/IAA protein

An Aux/IAA protein is a member of a plant regulatory protein family involved in repression of auxin-responsive gene expression. A protein in this family can influence transcriptional output through interactions with an auxin response factor; it should not be treated as simply another name for the auxin molecule itself.^[ref]

A 1997 experiment connected the family with a measurable regulatory effect. Researchers introduced reporter genes controlled by natural or synthetic auxin-response DNA elements together with genes encoding Aux/IAA-family proteins into carrot protoplasts. Increasing production of the tested regulatory proteins specifically repressed the reporter response. Separate binding and interaction assays supplied complementary evidence about the DNA element and the participating proteins.^[ref]

An original readout example keeps abundance and regulation separate. Suppose a normalized reporter gives100 units in a matched control and25 units when the candidate repressor is expressed. The reduction is $(100-25)/100=0.75$, or75 percent. These invented values describe the chosen reporter assay; they do not establish a75-percent reduction in every native auxin-regulated gene or in plant growth.

Controls should distinguish the intended response element from general loss of reporter production or viable protoplasts. A perturbation that reduces all expression could imitate repression in one readout. Conversely, interaction between two proteins alone does not demonstrate the magnitude or direction of a transcriptional effect. Combining a defined reporter with molecular interaction evidence helps connect a regulatory component to a specific response.