Isolation of a cDNA clone coding for an SB β-chain

Abstract

Class II antigens of the major histocompatibility complex (MHC) consist of a family of closely related cell surface-expressed glycoproteins. These antigens, which are genetically polymorphic, control important aspects of the immune response¹. At least three types of human class II antigens, namely, DR, DC and SB (refs 2–4), have been identified. All class II antigens are heterodimers composed of one α- and one β-chain. The genes for both types of subunits are encompassed within the MHC^5,6. The general features of the DC and DR antigens have recently been elucidated^7–15. Much less is known, however, about the SB molecules¹⁶. Here we describe the isolation of a cDNA clone as well as a genomic clone encoding a β-chain whose amino acid sequence is compatible with the partial amino-terminal sequence of SB β-chains¹⁶.