Invariant chain

HLA class II histocompatibility antigen gamma chain also known as HLA-DR antigens-associated invariant chain or CD74 (Cluster of Differentiation 74), is a protein that in humans is encoded by the CD74 gene. The invariant chain (Abbreviated Ii) is a polypeptide involved in the formation and transport of MHC class II protein. The cell surface form of the invariant chain is known as CD74.