Murine cell surface immunoglobulin: Two native IgD structures

Murine spleen cell surface IgD is found in two forms upon SDS-polyacrylamide gel electrophoresis under nonreducing conditions. Both IgD(I) and IgD(II) are present on the surface of intact cells and appear to be native structures. Neither form could be accounted for by proteolytic degradation or disulfide bond rearrangement. IgD (II) has an apparent m.w. of 150,000, approximately 33,000 daltons lower than that expected for an H₂L₂ structure. Significant variation in the relative amounts of IgD(I) and IgD(II) was found when mice of different strains were examined.