trans-Zeatin is a member of the plant hormone family known as ‘cytokinins’, which regulate cell division, development, and nutrient processing. The biosynthesis of cytokinins involves isoprenylation of ATP or ADP, with trans-Zeatin being produced by the removal of phosphate and riboside groups from adenine and oxidation by cytochrome P735A. trans-Zeatin evokes its effects through high affinity receptors, including Arabidopsis histidine kinases (AHK). The affinity of trans-zeatin for AHK3, which is important in mediating plant development, has been reported to be 1.3 nM.