Ammonium-induced internalisation of UapC, the general purine permease from Aspergillus nidulans

Fungal Genet Biol. 2004 Jan;41(1):42-51. doi: 10.1016/j.fgb.2003.09.003.


The Aspergillus nidulans UapC protein is a high-affinity, moderate-capacity, uric acid-xanthine transporter, which also displays a low transport capacity for hypoxanthine, adenine, and guanine. It has been previously shown that a functional UapC-GFP fusion protein localises at the plasma membrane. Here, we demonstrate that ammonium, a preferred nitrogen source, dramatically changes the subcellular distribution of UapC. After addition of ammonium, UapC-GFP is removed from the plasma membrane and is concentrated into the vacuolar compartment. A chimeric gene construct in which an inducible promoter, insensitive to nitrogen repression, drives the expression of UapC-GFP, allowed us to demonstrate that the ammonium-dependent redistribution of UapC can be dissociated from the transcriptional repression of the gene. These results provide further support for the occurrence of endocytosis and the lysosomal-endosomal function of the vacuolar compartment in A. nidulans.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aspergillus nidulans / drug effects*
  • Aspergillus nidulans / metabolism
  • Cell Membrane / metabolism
  • Enzyme Induction
  • Fungal Proteins / metabolism*
  • Luminescent Proteins / genetics
  • Luminescent Proteins / metabolism
  • Membrane Transport Proteins / metabolism*
  • Nucleobase Transport Proteins
  • Purines / metabolism
  • Quaternary Ammonium Compounds / pharmacology*


  • Fungal Proteins
  • Luminescent Proteins
  • Membrane Transport Proteins
  • Nucleobase Transport Proteins
  • Purines
  • Quaternary Ammonium Compounds
  • UapC protein, Aspergillus nidulans
  • purine permease