Ammonium-induced internalisation of UapC, the general
purine permease from
J, Harispe L, Scazzocchio C, Gorfinkiel L, Rosa AL.
de Quimica Biologica, Facultad de Ciencias Quimicas, Universidad
de Cordoba, Ciudad Universitaria, 5000 Cordoba, Argentina.
Aspergillus nidulans UapC protein is a high-affinity, moderate-capacity,
acid-xanthine transporter, which also displays a low transport capacity for
adenine, and guanine. It has been previously shown that a
UapC-GFP fusion protein localises at the plasma membrane. Here, we
that ammonium, a preferred nitrogen source, dramatically changes the
distribution of UapC. After addition of ammonium, UapC-GFP is
from the plasma membrane and is concentrated into the vacuolar
A chimeric gene construct in which an inducible promoter,
to nitrogen repression, drives the expression of UapC-GFP, allowed
to demonstrate that the ammonium-dependent redistribution of UapC can be
from the transcriptional repression of the gene. These results
further support for the occurrence of endocytosis and the
function of the vacuolar compartment in A. nidulans.