J chain biosynthesis in pre-B cells and other possible precursor B cells.
Human cell lines that resemble precursors in the B cell lineage have been found to synthesize J chain. In vivo pulse labeling, together with in vitro translation of total cellular RNA in a wheat germ cell-free system, detected the synthesis of J chain in immunoglobulin-secreting cell lines, in a cell line with only surface IgM, as well as in the pre-B-like cell line Josh 4 and the round cell lines Josh 7 and KLM 2. The primary translation products of J chain from all of these cell lines were found to be indistinguishable from one another by serologic criteria, by relative mobility on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, by charge as judged by alkaline-urea gel electrophoresis, and by peptide mapping. These findings suggest that the onset of J chain biosynthesis represents a relatively early event in B cell ontogeny, occurring before the development of immunoglobulin polymer-secreting cells. Its role may, consequently, be fundamental to the biosynthesis of all immunoglobulins, at different stages of B cell differentiation.
D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology*; D002460:Cell Line; D011232:Chemical Precipitation; D004854:Herpesvirus 4, Human / Q000276:immunology; D000949:Histocompatibility Antigens Class II; D006801:Humans; D007070:Immunoglobulin A / Q000096:biosynthesis; D007144:Immunoglobulin J-Chains / Q000096:biosynthesis*; D007075:Immunoglobulin M / Q000096:biosynthesis; D008715:Methionine / Q000378:metabolism; D011817:Rabbits
D000949:Histocompatibility Antigens Class II; D007070:Immunoglobulin A; D007144:Immunoglobulin J-Chains; D007075:Immunoglobulin M; D008715:Methionine