Aft1 is a transcriptional activator in Saccharomyces cerevisiae that responds to 
iron availability and regulates the expression of genes in the iron regulon, 
such as FET3, FTR1 and the ARN family. Using a two-hybrid screen, we found that 
Aft1 physically interacts with the FOB (ferrioxamine B) transporter Arn3. This 
interaction modulates the ability of Arn3 to take up FOB. The interaction 
between Arn3 and Aft1 was confirmed by beta-galactosidase, 
co-immunoprecipitation and SPR (surface plasmon resonance) assays. Truncated 
Aft1 had a stronger interaction with Arn3 and caused a higher FOB-uptake 
activity than full-length Aft1. Interestingly, only full-length Aft1 induced the 
correct localization of Arn3 in response to FOB. Furthermore, we found Aft1 
affected Arn3 ubiquitination. These results suggest that Aft1 interacts with 
Arn3 and may regulate the ubiquitination of Arn3 in the cytosolic compartment.