Ca entry at the plasma membrane and uptake by acidic stores is regulated by the activity of the V-H -ATPase in Toxoplasma gondii.

Ca is a universal intracellular signal that regulates many cellular functions. In Toxoplasma gondii, the controlled influx of extracellular and intracellular Ca into the cytosol initiates a signaling cascade that promotes pathogenic processes like tissue destruction and dissemination. In this work, we studied the role of proton transport in cytosolic Ca homeostasis and the initiation of Ca signaling.

The Toxoplasma Vacuolar H-ATPase Regulates Intracellular pH and Impacts the Maturation of Essential Secretory Proteins.

Vacuolar-proton ATPases (V-ATPases) are conserved complexes that couple the hydrolysis of ATP to the pumping of protons across membranes. V-ATPases are known to play diverse roles in cellular physiology. We studied the Toxoplasma gondii V-ATPase complex and discovered a dual role of the pump in protecting parasites against ionic stress and in the maturation of secretory proteins in endosomal-like compartments.

Characterization of Two EF-hand Domain-containing Proteins from Toxoplasma gondii.

The universal role of calcium (Ca ) as a second messenger in cells depends on a large number of Ca -binding proteins (CBP), which are able to bind Ca through specific domains. Many CBPs share a type of Ca -binding domain known as the EF-hand. The EF-hand motif has been well studied and consists of a helix-loop-helix structural domain with specific amino acids in the loop region that interact with Ca .