text: Derivatives of the molecule BAPTA bind to this element in an imaging technique which measures concentrations of it.
full_question: Derivatives of the molecule BAPTA bind to this element in an imaging technique which measures concentrations of it. The TRP5 receptor mediates levels of this element in podocytes. RNA editing of glutamine to arginine in the AMPA receptor results in its inability to uptake this element. A halide of this element is commonly used to induce artificial competence by shielding lipopolysaccharides and phospholipids, allowing DNA to enter cell membranes. Uptake of this element into the cytosol of (*) astrocytes results in the release of glutamate into the extracellular space. The photoprotein aequorin is notable for having three motifs which function as binding sites to this element known as EF hands. Inositol triphosphate binds to the Ins3P receptor to release this element from the ER into the cytoplasm. The binding of this element to actin exposes the myosin binding site, allowing cross linking and ultimately muscle contraction. For ten points, identify this element whose carbonate commonly makes up shells.
first_sentence: Derivatives of the molecule BAPTA bind to this element in an imaging technique which measures concentrations of it.