Plant hormone strigolactones regulate branching by maintaining the dormant state of axillary buds. A receptor for strigolactones remained unknown, though previous work had implicated a handful of genes in the response to these hormones. Now work from Snowden and colleagues indicates that the product of one such gene, DAD2 in petunia (D14 in Oryza sativa and Arabidopsis thaliana), is a receptor for strigolactones. The authors cloned the DAD2 gene and solved the crystal structure of the protein, revealing an α/β hydrolase fold with a large cavity and a canonical catalytic triad. The cavity is L-shaped and strongly hydrophobic, and it could accommodate strigolactones. In fact, the thermal stability of DAD2 is reduced in the presence of the synthetic strigolactone GR24, indicating protein conformational changes. In addition, when GR24 was incubated with DAD2, the hormone was cleaved into products that lacked inhibitory activity on bud growth. The authors then queried DAD2's interactions with other factors involved in strigolactone signaling. They found that DAD2 interacts with F-box protein PhMAX2A but only in the presence of GR24 and in a dose-dependent manner. A catalytically inactive DAD2 mutant could not complement the dad2 mutation; it was also unable to interact with PhMAX2A in the presence of GR24 or added cleavage products. The authors propose that structural changes in DAD2 that take place after strigolactone binding, perhaps due to the formation of a reaction intermediate, are required for DAD2 to interact with PhMAX2A and hence for signal transduction. This hypothesis is consistent with previous observations that strigolactone analogs that are resistant to cleavage are also inactive. (Curr. Biol. published online 6 September 2012, doi:10.1016/j.cub.2012.08.007)