PMID:21335528

Citation	Bowman, BJ, Abreu, S, Margolles-Clark, E, Draskovic, M and Bowman, EJ (2011) Role of four calcium transport proteins, encoded by nca-1, nca-2, nca-3, and cax, in maintaining intracellular calcium levels in Neurospora crassa. Eukaryotic Cell 10:654-61
Abstract	We have examined the distribution of calcium in Neurospora crassa and investigated the role of four predicted calcium transport proteins. The results of cell fractionation experiments showed 4% of cellular calcium in mitochondria, approximately 11% in a dense vacuolar fraction, 40% in an insoluble form that copurifies with microsomes, and 40% in a high-speed supernatant, presumably from large vacuoles that had broken. Strains lacking NCA-1, a SERCA-type Ca(2+)-ATPase, or NCA-3, a PMC-type Ca(2+)-ATPase, had no obvious defects in growth or distribution of calcium. A strain lacking NCA-2, which is also a PMC-type Ca(2+)-ATPase, grew slowly in normal medium and was unable to grow in high concentrations of calcium tolerated by the wild type. Furthermore, when grown in normal concentrations of calcium (0.68 mM), this strain accumulated 4- to 10-fold more calcium than other strains, elevated in all cell fractions. The data suggest that NCA-2 functions in the plasma membrane to pump calcium out of the cell. In this way, it resembles the PMC-type enzymes of animal cells, not the Pmc1p enzyme in Saccharomyces cerevisiae that resides in the vacuole. Strains lacking the cax gene, which encodes a Ca(2+)/H(+) exchange protein in vacuolar membranes, accumulate very little calcium in the dense vacuolar fraction but have normal levels of calcium in other fractions. The cax knockout strain has no other observable phenotypes. These data suggest that "the vacuole" is heterogeneous and that the dense vacuolar fraction contains an organelle that is dependent upon the CAX transporter for accumulation of calcium, while other components of the vacuolar system have multiple calcium transporters.
Links	PubMed PMC3127652 Online version:10.1128/EC.00239-10
Keywords	Adenosine Triphosphatases/genetics; Adenosine Triphosphatases/metabolism; Calcium/metabolism; Fungal Proteins/genetics; Fungal Proteins/metabolism; Membrane Transport Proteins/genetics; Membrane Transport Proteins/metabolism; Neurospora crassa/enzymology; Neurospora crassa/metabolism; Saccharomyces cerevisiae/metabolism
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
NEUCS:Q9UUY2		GO:0070588: calcium ion transmembrane transport	ECO:0000315:		P		Figure 4 shows accumulation of intracellular Ca+ in a strain that lacks nca2	complete CACAO 6034
NEUCS:Q9UUY2	involved_in	GO:0070588: calcium ion transmembrane transport	ECO:0000315: mutant phenotype evidence used in manual assertion		P		Seeded From UniProt	complete

References

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