Chromogranin B (CHGB) is a member of the granin family of acidic, soluble glycoproteins predominantly found in the secretory granules of neuroendocrine cells, including neurons, endocrine cells, and certain tumors. It is structurally and functionally related to chromogranin A (CHGA), though differences in their distribution and proteolytic processing suggest distinct roles. CHGB is co-released with hormones, neuropeptides, and neurotransmitters upon cellular stimulation, serving as a key component in the regulated secretory pathway.
Functionally, CHGB acts as a prohormone, yielding bioactive peptides like secretolytin and PE-11 through proteolytic cleavage, which may modulate antimicrobial activity, vascular function, or cell signaling. It also plays a role in granule biogenesis, stabilizing intra-granular pH and hormone storage via its calcium-binding capacity.
Antibodies targeting CHGB are widely used in research and diagnostics. In clinical pathology, CHGB antibodies serve as immunohistochemical markers to identify neuroendocrine tumors (e.g., pheochromocytomas, neuroblastomas) and differentiate them from non-endocrine neoplasms. Elevated circulating CHGB levels, detected via immunoassays, correlate with tumor burden and are monitored in conditions like heart failure or neurodegenerative diseases.
Research applications include studying secretory mechanisms, neuroendocrine system dynamics, and CHGB's involvement in stress responses. Recent studies also explore its potential role in autoimmune disorders and neurodegeneration, though mechanisms remain unclear. Despite its diagnostic utility, CHGB's functional complexity necessitates careful interpretation in experimental and clinical contexts.