Stability of the B cell antigen receptor complex

The B cell antigen receptor (BCR) comprises the membrane-bound immunoglobul in (mIg) molecule and the Ig-alpha/Ig-beta heterodimer. By comparing the st ability of the IgD-BCR and IgM-BCR in different detergent lysates, we find that the IgD-BCR is more stable than the IgM-BCR. Analysis of chimeric mIgD molecules suggests that the delta m transmembrane region is responsible fo r the more stable association of mIgD with the Ig-alpha/Ig-beta heterodimer . Further, the differential glycosylation of Ig-alpha molecules, in the two different BCR complexes, is determined solely by the ectodomains of the mi g molecules. The implications of these findings for the intracellular trans port and the signalling capacity of the BCRs are discussed. (C) 2000 Elsevi er Science Ltd. All rights reserved.