SYNTHESIS AND OLIGOSACCHARIDE PROCESSING OF IMMUNOGLOBULIN-M DURING B-CELL DIFFERENTIATION.
AuthorCHEN, WENDY YUNTIEN.
AdvisorGrimes William J.
MetadataShow full item record
PublisherThe University of Arizona.
RightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
AbstractIn order to understand glycoprotein biosynthesis and processing, we have studied the glycosylation and intracellular assembly kinetics of murine IgM which are expressed functionally only at specific stages of B-cell differentiation by the corresponding tumor cell lines. We have shown that the majority of carbohydrate chains on intracellular IgM contain predominantly Man₈GlcNac₂ rate limiting step in the carbohydrate processing is the transport from the RER to the Golgi apparatus. We made comparisons of carbohydrate structures on secretory and membrane-bound u chains produced by different cell lines. Our results show that the carbohydrates on WEHI231 membrane-bound IgM are less processed, and the processing at individual glycosylation sites is different for IgMs produced by plasmacytoma (MOPC104E) and hybridoma (MPC11xW279.2) cell lines. In addition, we also show that the glycosylation and processing are dramatically altered by lowering the glucose concentration in the cell culture medium. These results are a beginning for our understanding of the influence of the polypeptide on the final glycosylation patterns of a glycoprotein, and the genetic and environmental control over the carbohydrate processing during intracellular transport. The kinetic studies on IgM synthesis and maturation in WEHI231 as well as WEHI279.1/12 cells have led to the conclusion that membrane bound IgM and soluble IgM are segregated and processed individually even in the same cell. These differences appear to lead to the changes in carbohydrate/processing for membrane-bound and soluble IgM.