Temporal relationship of translation and glycosylation of immunoglobulin heavy and light chains

Abstract

The initial glycosylation of MPC 11 .gamma.2b H-chains occurs quantitatively in vivo when the nascent H-chains reach a size of approximately 38,000 daltons. Nonglycosylated, completed MPC 11 H-chains cannot be glycosylated in these cells. Other classes of mouse H-chains (i.e., .mu., .alpha., and .gamma.1) appear to be glycosylated as nascent chains; nonglycosylated, completed H-chains cannot be glycosylated by the cell in any of these cases. Variant MPC 11 cells synthesizing a H-chain with a carboxy-terminal deletion appear to glycosylate some H-chains prior to chain completion and some H-chains after chain completion and release from the polysomes. Similar to the variant MPC 11 cells, MOPC 46B cells (which synthesize a .kappa. L-chain containing an oligosaccharide attached to an asparagine located 28 residues from the amino terminus) glycosylate the majority of L-chains prior to chain completion and some L-chains after chain completion and release from the polysomes. Although completed MOPC 46B L-chains can be glycosylated if they are present in a monomeric form, they apparently cannot be glycosylated if they are present in a covalent dimeric form.