Binding to and responding, e.g. by conformational change, to changes in the cellular level of calcium ions (Ca2+). [ http://www.ncbi.nlm.nih.gov/pubmed/17020874 http://www.ncbi.nlm.nih.gov/pubmed/28151650 http://www.ncbi.nlm.nih.gov/pubmed/16005298 ]
This is just here as a test because I lose it