Calretinin--sensor or buffer--function still unclear

Calretinin (CR) is a 31.5 kDa EF-hand calcium binding protein. CR has a general neuronal localization and is a predominantly cytosolic protein. The biochemical properties of this protein are well characterized but its function is still unclear. It is often postulated that the presence of CR correlates with an increased survival ability of cells under pathological conditions connected with increased intracellular calcium levels. However, not all studies confirm such a relationship and they indicate that the presence of CR does not protect cells against calcium overload and that CR does not act as an intracellular calcium buffer. Recent results concerning CR function are discussed and the conclusion is proposed that CR acts as a calcium modulator rather than a calcium buffer.