May be involved in nodule organogenesis rather in the processes related to nitrogen fixation or interactions with the bacteria. May regulate nodulation by controlling the levels of freely available cytokinins. Homodimer. Expressed in nodules, but not in leaves, stems, flowers and roots. Specifically located in the nodule cortex. Up-regulated during nodulation, but not by Nod factors or pathogen infection. The NT13 molecules that have dimerized without cytokinin ligand most probably lose their binding properties because it seems unlikely that the dimer can dissociate back to the monomer. Asp-62 from the complementary protein molecule forms hydrogen bonds with the cytokinin scaffold. Belongs to the BetVI family.