Ca2+ transport in Saccharomyces cerevisiae.
Cytosolic free Ca2+ is maintained at submicromolar levels in budding yeast by the activity of Ca2+ pumps and antiporters. We have recently identified the structural genes for two Ca2+ pumps, PMC1 [correction of PCM1] and PMR1, which are required for Ca2+ sequestration into the vacuole and secretory organelles, respectively. The function of either Ca2+ pump is sufficient for yeast viability, but deletion of both genes is lethal because of elevation of cytosolic [Ca2+] and activation of calcineurin, a Ca(2+)- and calmodulin-dependent protein phosphatase. Calcineurin activation decreases Ca2+ sequestration in the vacuole by a putative Ca2+ antiporter and may also increase Ca2+ pump activity. These regulatory processes can affect the ability of yeast strains to tolerate high extracellular [Ca2+]. We propose a model in which the cellular response to changes in the environmental levels of Ca2+ is mediated by calmodulin and calcineurin which, in turn, modulate the various types of Ca2+ transporters.
Cunningham
K W
KW
Whitehead Institute for Biomedical Research, Massachusetts Institute of Technology, 9 Cambridge Center 02142.
Fink
G R
GR
D000818:Animals; D017920:Antiporters / Q000378:metabolism*; D019703:Calcineurin; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000235:genetics / Q000378:metabolism*; D002148:Calmodulin-Binding Proteins / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005800:Genes, Fungal; D008954:Models, Biological; D010749:Phosphoprotein Phosphatases / Q000378:metabolism; D010802:Phylogeny; D051381:Rats; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D014617:Vacuoles / Q000378:metabolism
D017920:Antiporters; D015220:Calcium Channels; D002148:Calmodulin-Binding Proteins; D019703:Calcineurin; D010749:Phosphoprotein Phosphatases; D000252:Calcium-Transporting ATPases; D002118:Calcium