Chromogranin A or parathyroid secretory protein 1 (gene name CHGA) is a member of the granin

Granin

Granin could be:* Granin, a protein family* Daniil Granin, a novelist* Aleksandr Leonovitch Granin, a character in Metal Gear Solid 3: Snake Eater...

 family of neuroendocrine secretory proteins, i.e. it is located in secretory vesicles of neurons and endocrine cells. In humans, chromogranin A protein

Protein

Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

 is encoded by the CHGA gene

Gene

A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...

.

Tissue distribution

Examples of cells producing chromogranin A are chromaffin cells of the adrenal medulla

Adrenal medulla

The adrenal medulla is part of the adrenal gland. It is located at the center of the gland, being surrounded by the adrenal cortex. It is the innermost part of the adrenal gland, consisting of cells that secrete epinephrine , norepinephrine , and a small amount of dopamine in response to...

, paraganglia

Paraganglia

The paraganglia are small groups of chromaphil cells connected with the ganglia of the sympathetic trunk and the ganglia of the celiac, renal, suprarenal, aortic and hypogastric plexuses...

, enterochromaffin-like cell

Enterochromaffin-like cell

Enterochromaffin-like cells or ECL cells are a type of neuroendocrine cells found in the gastric glands of the gastric mucosa beneath the epithelium, in particular in the vicinity of parietal cells. They are also considered a type of enteroendocrine cell....

s and beta cell

Beta cell

Beta cells are a type of cell in the pancreas located in the so-called islets of Langerhans. They make up 65-80% of the cells in the islets.-Function:...

s of the pancreas.

Function

Chromogranin A is the precursor to several functional peptides including vasostatin, pancreastatin, catestatin and parastatin. These peptides negatively modulate the neuroendocrine function of the releasing cell (autocrine) or nearby cells (paracrine). Other peptides derived from chromogranin A with uncertain function include chromostatin, WE-14 and GE-25.

Chromogranin A might promote the generation of secretory granules.

Clinical significance

Chromogranin A is elevated in pheochromocytoma

Pheochromocytoma

A pheochromocytoma or phaeochromocytoma is a neuroendocrine tumor of the medulla of the adrenal glands , or extra-adrenal chromaffin tissue that failed to involute after birth and secretes excessive amounts of catecholamines, usually noradrenaline , and adrenaline to a lesser extent...

s.

It is used as an indicator for pancreas and prostate cancer

Prostate cancer

Prostate cancer is a form of cancer that develops in the prostate, a gland in the male reproductive system. Most prostate cancers are slow growing; however, there are cases of aggressive prostate cancers. The cancer cells may metastasize from the prostate to other parts of the body, particularly...

 and in carcinoid syndrome

Carcinoid syndrome

Carcinoid syndrome refers to the array of symptoms that occur secondary to carcinoid tumors. The syndrome includes flushing and diarrhea, and, less frequently, heart failure and bronchoconstriction...

. It might play a role in early neoplasic progression. It is also elevated in diabetes. Chromogranin A is cleaved by an endogenous prohormone convertase to produce several peptide fragments. See chromogranin A GeneRIFs for references.

External links

• chromogranin A antibody stains via Google Image http://images.google.com/images?q=chromogranin+A