Structure and function of murine class II major histocompatibility complex genes

Abstract

The I region of the murine major histocompatibility complex (MHC) was first identified as a locus containing genes controlling specific immune responses (Ir genes). The same chromosomal segment was also found to include genes encoding highly polymorphic membrane antigens termed Ia (for I-region-associated) antigens. A combination of immunogenetic, serologic, and biochemical investigations demonstrated that the Ia antigens are heterodimeric cell surface glycoproteins, consisting of one heavy (α) and one light (β) chain in noncovalent association. Two isotypic forms of Ia are found in mice: I-A (A(β):A(α)) and I-E (E(β):E(α)). We now know that Ir genes are the structural genes for Ia molecules..