Member of the granin protein family that regulates the biogenesis of secretory granules (PubMed:19357184). Acts as a sorting receptor for intragranular proteins including chromogranin A/CHGA (By similarity). May also play a role in angiogenesis. Promotes endothelial proliferation, migration and tube formation through MEK/ERK signaling pathway (PubMed:29154827). Interacts with CHGA (PubMed:19357184) (By similarity). Interacts with secretogranin II/SCG2 (PubMed:19357184). Interacts (via C-terminus) with CPE (By similarity). Associated with the secretory granule membrane through direct binding to cholesterol-enriched lipid rafts. Expressed in brain, heart, kidney, liver and skeletal muscle. O-glycosylated. Polymorphisms in the 5'-flanking region and in intron 1 may have an effect on transcriptional activity and be associated with an increase in subcutaneous, but not visceral, fat area. Hence, may influence the risk of obesity.