LMAN1

ERGIC-53 (also named LMAN1) is a type I integral membrane protein localized in the intermediate region (ERGIC) between the endoplasmic reticulum and the Golgi, presumably recycling between the two compartments. 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.^[8][7] MCFD2 is the second gene that leads to combined deficiency of factor V-factor VIII.^[9] 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,^[10]as illustrated here.^[8]

LMAN1 mutational inactivation is a frequent and early event potentially contributing to colorectal tumorigenesis.^[11]