3T4L:
reference: Structural basis for cytokinin recognition by Arabidopsis thaliana histidine kinase 4., Hothorn M, Dabi T, Chory J, Nat Chem Biol. 2011 Oct 2;7(11):766-8. doi: 10.1038/nchembio.667. PMID: 21964459

This OCA Structure page
uses Jmol, developed by the Jmol Development Team (documentation).