Previous work from our laboratories demonstrated that the sugar-induced activation of plasma membrane
H+-ATPase in Saccharomyces cerevisiae is dependent on calcium metabolism with the contribution
of calcium influx from external medium. Our results demonstrate that a glucose-induced calcium (GIC)
transporter, a new and still unidentified calcium carrier, sensitive to nifedipine and gadolinium and
activated by glucose addition, seems to be partially involved in the glucose-induced activation of the
plasma membrane H+-ATPase. On the other hand, the importance of calcium carriers that can release
calcium from internal stores was analyzed in glucose-induced calcium signaling and activation of plasma
membrane H+-ATPase, in experimental conditions presenting very low external calcium concentrations.
Therefore the aim was also to investigate how the vacuole, through the participation of both Ca2+-ATPase
Pmc1 and the TRP homologue calcium channel Yvc1 (respectively, encoded by the genes PMC1 and YVC1)
contributes to control the intracellular calcium availability and the plasma membrane H+-ATPase activation
in response to glucose. In strains presenting a single deletion in YVC1 gene or a double deletion
in YVC1 and PMC1 genes, both glucose-induced calcium signaling and activation of the H+-ATPase are
nearly abolished. These results suggest that Yvc1 calcium channel is an important component of this signaltransductionpathway
activated inresponse to glucose addition.We also found that by a still undefined
mechanism Yvc1 activation seems to correlate with the changes in the intracellular level of IP3. Taken
together, these data demonstrate that glucose addition to yeast cells exposed to low external calcium
concentrations affects calcium uptake and the activity of the vacuolar calcium channel Yvc1, contributing
to the occurrence of calcium signaling connected to plasma membrane H+-ATPase activation