Member of the granin protein family that regulates the biogenesis of secretory granules (By similarity). 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 (By similarity). Interacts with CHGA (By similarity). Interacts with secretogranin II/SCG2 (By similarity). Interacts (via C-terminus) with CPE (By similarity). Associated with the secretory granule membrane through direct binding to cholesterol-enriched lipid rafts. Contaminating sequence. Potential poly-A sequence. Contaminating sequence. Potential poly-A sequence.