title: Ammonium-induced internalisation of UapC, the general purine permease from Aspergillus nidulans.
abstract: 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.
authors.affiliation: Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, 5000 Córdoba, Argentina. jvaldez@mrc-lmb.cam.ac.uk
authors.forename: Javier
authors.initials: J
authors.lastname: Valdez-Taubas
authors.forename: Laura
authors.initials: L
authors.lastname: Harispe
authors.forename: Claudio
authors.initials: C
authors.lastname: Scazzocchio
authors.forename: Lisette
authors.initials: L
authors.lastname: Gorfinkiel
authors.forename: Alberto L
authors.initials: AL
authors.lastname: Rosa
mesh_terms: D001233:Aspergillus nidulans / Q000187:drug effects* / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D004790:Enzyme Induction; D005656:Fungal Proteins / Q000378:metabolism*; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000378:metabolism*; D033702:Nucleobase Transport Proteins; D011687:Purines / Q000378:metabolism; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology*
chemical_list: D005656:Fungal Proteins; D008164:Luminescent Proteins; D026901:Membrane Transport Proteins; D033702:Nucleobase Transport Proteins; D011687:Purines; D000644:Quaternary Ammonium Compounds; C114088:UapC protein, Aspergillus nidulans; C022483:purine permease