Probable molecular chaperone assisting protein biosynthesis and transport in the endoplasmic reticulum (By similarity). Required for the proper biosynthesis and transport of pulmonary surfactant-associated protein A/SP-A, pulmonary surfactant-associated protein D/SP-D and the lipid transporter ABCA3 (By similarity). By regulating both the proper expression and the degradation through the endoplasmic reticulum-associated protein degradation pathway of these proteins plays a crucial role in pulmonary surfactant homeostasis (By similarity). Has an anti-fibrotic activity by negatively regulating the secretion of type I and type III collagens (By similarity). This calcium-binding protein also transiently associates with immature PCSK6 and regulates its secretion (By similarity). Interacts with PCSK6 (immature form including the propeptide); probably involved in the maturation and the secretion of PCSK6. N-glycosylated. Degraded by PCSK6 and other endoproteases including FURIN and PCSK5. Belongs to the CREC family.