K+ uptake systems in the yeast Hansenula polymorpha. Transcriptional and post-translational mechanisms involved in high-affinity K+ transporter regulation

► Hak1 and Trk1 are two plasma membrane K+ transporters in Hansenula. ► Hak1 is the high affinity K+ transporter in Hansenula polymorpha. ► Calcineurin is involved in the transcriptional regulation of HAK1. ► Hak1 is internalized and degraded in the vacuole in response to the presence of K+. ► That process is dependent on the ubiquitin ligase Rsp5.