Structure function analysis of the H-2 Abp gene.

The gene encoding the H-2 Ap class II beta chain was isolated from a B10.P genomic library and sequenced. This gene was also used to construct transfectants of the CH12 lymphoma clone CH12.LX, which express the Abp gene product in association with the endogenous A alpha k chain. We present here the first report of the complete nucleotide coding sequence of Abp. The predicted amino acid sequence of Abp reveals only five residues different from Abq, four of which are present in the mature peptide. These four amino acid changes could account for the differential susceptibility of H-2q vs H-2p mice to the development of collagen-induced arthritis (CIA). Antibodies specific for the transfected Abp protein induce CH12.LX cells to secrete immunoglobulin in the presence of antigen. Comparison of the amino acid sequence with other A beta chains that have been tested in signal transduction experiments suggests that amino acid 9 may be important to the signaling ability of class II A molecules.