Member of the granin protein family that regulates the biogenesis of secretory granules (PubMed:16219686). Acts as a sorting receptor for intragranular proteins including chromogranin A/CHGA (PubMed:12388744). May also play a role in angiogenesis (PubMed:28330905). Promotes endothelial proliferation, migration and tube formation through MEK/ERK signaling pathway (By similarity). Interacts with CHGA (PubMed:12388744). Interacts with secretogranin II/SCG2 (By similarity). Interacts (via C-terminus) with CPE (PubMed:16219686). Associated with the secretory granule membrane through direct binding to cholesterol-enriched lipid rafts. Expressed in various brain areas, with highest levels in the arcuate nucleus and the lateral hypothalamic area, as well as the paraventricular nucleus and the ventromedial hypothalamus (at protein level).