The landscape of cytokinin binding by a plant nodulin

The crystal structures of complexes of M. truncatula nodulin 13 with four cytokinins, trans-zeatin, N⁶-isopentenyladenine, kinetin and N⁶-benzyladenine, show an unusual mode of dimerization of this PR-10-fold plant protein. The cytokinin-binding mode in the internal cavity of the protein is the same in each complex and resembles the pattern found in the cytokinin receptor protein.