SRGN is known as a hematopoietic cell granule proteoglycan. Proteoglycans stored in the secretory granules of various hematopoietic cells has a protease-resistant peptide core, and is vital for neutralizing hydrolytic enzymes. SRGN is associated with the macromolecular complex of granzymes and perforin, which may serve as a mediator of granule-mediated apoptosis. It is required for storage of some proteases in both connective tissue and mucosal mast cells and for storage of granzyme B in T-lymphocytes. SRGN also plays a role in localizing neutrophil elastase in azurophil granules of neutrophils.