ABLs and transmembrane kinases shape extracellular auxin perception

Auxin is a key phytohormone, but the mechanism underlying apoplastic auxin perception has remained elusive. Yu et al. recently demonstrated that the interaction of two novel apoplast-localized auxin-binding protein 1 (ABP1)-like proteins, ABL1 and ABL2, with transmembrane kinases (TMKs) shapes extracellular auxin perception in both an overlapping and an ABP1-independent manner.