Vitamin D helps maintain the levels of phosphorus and this element, which is used to synthesize hydroxyapatite by osteoblasts.
Proteins that bind to this element, such as parvalbumin, often feature the "EF hand" motif. Although the PMCA protein has a higher affinity for this element's ion, a protein that has a higher capacity for exchanging this element's ions with sodium ions is responsible for removing this element from a cell after a cardiac action potential. Ions of this element bind to a troponin complex after they are released by the sarcoplasmic reticulum to initiate muscle contraction. Vitamin D helps maintain the levels of phosphorus and this element, which is used to synthesize hydroxyapatite by osteoblasts. For 10 points, identify this alkali metal found in bones and teeth.
Proteins that bind to this element, such as parvalbumin, often feature the "EF hand" motif.
calcium [or Ca; or Ca2+