Plants, just like animals, contain growth promoting steroid hormones. The active hormone is sensed at the plasma membrane by a plant-unique receptor kinase. For activation, the plant steroid receptor relies on a shape-complementary helper protein. Researchers from Michael Hothorn‘s team have now uncovered that these helper proteins are targeted by other receptor kinases termed BIR proteins. The steroid receptor and BIRs compete for binding to the helper protein, thereby shaping plant growth in different cells and tissues. The study was published on May 07, 2018 in Nature Plants.