Strongly inhibits glucose induced insulin release from the pancreas. Inhibits catecholamine release from chromaffin cells and noradrenergic neurons by acting as a non-competitive nicotinic cholinergic antagonist. Can induce mast cell migration, degranulation and production of cytokines and chemokines. Regulates granule biogenesis in endocrine cells by up-regulating the transcription of protease nexin 1 (SERPINE2) via a cAMP-PKA-SP1 pathway. This leads to inhibition of granule protein degradation in the Golgi complex which in turn promotes granule formation (PubMed:21436258). Pyroglutaminated (pGlu)-serpinin exerts an antiapoptotic effect on cells exposed to oxidative stress (PubMed:21537909). Interacts with SCG3; this interaction is optimal in conditions mimicking the lumenal milieu of the trans-Golgi network, i.e. pH 5.5 and 10 mM Ca(+2). Associated with the secretory granule membrane through direct interaction to SCG3 that in turn binds to cholesterol-enriched lipid rafts in intragranular conditions. Pyroglutaminated serpinin localizes to secretory vesicle. CgA is O-glycosylated. With pyrrolidone carboxylic acid at Gln-438. Binds calcium with a low-affinity. Belongs to the chromogranin/secretogranin protein family.