The protein encoded by this gene is a membrane mannose-specific lectin that cycles between the endoplasmic reticulum, endoplasmic reticulum-Golgi intermediate compartment, and cis-Golgi, functioning as a cargo receptor for glycoprotein transport. The protein has an N-terminal signal sequence, a calcium-dependent and pH-sensitive carbohydrate recognition domain, a stalk region that functions in oligomerization, a transmembrane domain, and a short cytoplasmic domain required for organelle targeting. Allelic variants of this gene are associated with the autosomal recessive disorder combined factor V-factor VIII deficiency. The protein is a mannose-specific lectin and is a member of a novel family of plant lectin homologs in the secretory pathway of animal cells. Mutations in the gene are associated with a coagulation defect. Using positional cloning, the gene was identified as the disease gene leading to combined deficiency of factor V-factor VIII, a rare, autosomal recessive disorder in which both coagulation factors V and VIII are diminished. MCFD2 is the second gene that leads to combined deficiency of factor V-factor VIII. ERGIC-53 and MCFD2 form a protein complex and serve as a cargo receptor to transport FV and FVIII from the ER to the ERGIC and then the Golgi, as illustrated here.