Description
Chromogranin A (CGA) is a hydrophilic and acidic protein of 439 aa (49 kD) present in the chromaffin granules of neuroendocrine cells.
It is part of the granin family. CGA is thought to act as a pro-hormone. Its proteolysis is a key component of its physiology. This degradation releases biologically active peptides (vasostatins, chromostatin, pancreastatin, parastatin), which possess different paracrine and autocrine functions. This proteolysis is tissue-specific and fragmentation of the protein is different depending on its location. It primarily takes place in the cell, inside chromaffin granules. In immunohistochemistry, the presence of CGA in tumour cells is suggestive of a neuroendocrine origin of the tumour. Circulating CGA exists in healthy subjects and the values obtained are independent of age and gender.
