Calcium ions are one of the key mediators in the cell. Their action takes place, inter alia, through the calcium-binding proteins. Among the calcium-binding proteins are a growing number of discovered in the past ten years, protein motif "EF-hand" which form the so-called family. Sensors neuronal calcium (NCS, Neuronal Calcium Sensors). It belong to, inter alia: rekoweryny, frekweniny protein GCAP, VILIP protein. Their common feature is the presence of a characteristic structure and in certain nerve cells, which suggests that there remain a precise function.