2.A.7.19.3
Ureide Permease 5, UPS5 of 415 aas and 10 TMSs.  Proton-coupled transporter that transports a wide spectrum of oxo derivatives of heterocyclic nitrogen compounds, including allantoin, uric acid and xanthine, but not adenine. UPS5 mediates transport of uracil and 5-fluorouracil (a toxic uracil analog) (Schmidt et al. 2006).  Allantoin accumulation mediated by UPS5 confers salt stress tolerance (Lescano et al. 2016). AtUPS5-Long and AtUPS5-Short localization indicates that they play different roles in allantoin distribution between subcellular compartments. Thus, Lescano et al. 2019 predict that under non-stress conditions UPS5L and UPS5S may function in allantoin degradation pathway for nutrient recycling, whereas under stress conditions, both splice variants are involved in cell export via vesicles of the secretory pathway, allowing allantoin translocation from roots to shoots.