NPF (NRT1/PTR FAMILY) proteins were originally identified as nitrate or di/tri-peptide transporters. However, recent studies revealed that the members of this transporter family also transport plant hormones, including auxin (indole-3-acetic acid; IAA), abscisic acid (ABA) and gibberellin (GA), as well as secondary metabolite, such as glucosinolates. In the present study, I developed the modified yeast two-hybrid (Y2H) systems with the receptor complexes for GA and Jasmonates (JA-Ile) to detect the hormone transport activities of proteins expressed in the yeast cells. By using the Y2H receptor complex systems for ABA, GA and JA-Ile, I determined the activities of Arabidopsis NPFs for ABA, GA and JA-Ile transport. Several NPFs induced the formation of receptor complexes under relatively low hormone concentrations. Hormone transport activities were confirmed for some NPFs by direct analysis of hormone uptake of yeast cells using liquid chromatography-tandem mass spectrometry (LC-MS/MS). These results suggested that at least some NPF proteins function as hormone transporters in vivo.首都大学東京, 2015-03-25, 博士（理学）, 甲第533号首都大学東
