STRUCTURE-FUNCTION ANALYSIS OF THE H-2 ABP GENE

The gene encoding the H-2 A(p) class II beta-chain was isolated from a B1O.P genomic library and sequenced. This gene was also used to construct transfectants of the CH12 lymphoma clone CH12.LX, which express the Ab(p) gene product in association with die endogenous A(alpha)k chain. We present here the first report of the complete nucleotide coding sequence of Ab(p). The predicted amino acid sequence of Ab(p) reveals only five residues different from Ab(q), four of which are present in the mature pep tide. These four amino acid changes could account for the differential susceptibility of H-2(q) vs H-2(p) mice to die development of collagen-induced arthritis (CIA). Antibodies specific for the transfected Ab(p) 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.