V region carbohydrate and antibody expression.
N-Linked carbohydrates are frequently found in the V region of Ig H chains and can have a positive or negative effect on Ag binding affinity. We have studied a murine anti-alpha(1-->6) dextran V(H) that contains a carbohydrate in complementarity-determining region 2 (CDR2). This carbohydrate remains high mannose rather than being processed to a complex form, as would be expected for glycans on exposed protein loops. We have shown that the glycan remained high mannose when murine-human chimeric Abs were produced in a variety of cell types. Also, when another carbohydrate was present in CDR1, CDR2, or CDR3 of the L chain, the V(H) CDR2 glycan remained high mannose. Importantly, we found that when the anti-dextran V(H) CDR2 replaced CDR2 of an anti-dansyl V(H), the glycosylation site was used, but H chains were withheld in the endoplasmic reticulum and did not traffic to the Golgi apparatus. These results suggest that inappropriate V region glycosylation could contribute to ineffective Ab production from expressed Ig genes. In some cases, a carbohydrate addition sequence generated by either V region rearrangement or somatic hypermutation may result in an Ab that cannot be properly folded and secreted.
Gala
Françoise A
FA
Department of Microbiology, Immunology, and Molecular Genetics, The Molecular Biology Institute, University of California, Los Angeles, CA 90095, USA.
Morrison
Sherie L
SL
D000595:Amino Acid Sequence; D000818:Animals; D001216:Asparagine / Q000235:genetics; D001666:Binding Sites, Antibody / Q000235:genetics; D016466:CHO Cells; D002236:Carbohydrate Conformation; D002460:Cell Line; D045744:Cell Line, Tumor; D022801:Complementarity Determining Regions / Q000235:genetics; D006224:Cricetinae; D003911:Dextrans / Q000235:genetics / Q000276:immunology* / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000276:immunology; D005822:Genetic Vectors; D006031:Glycosylation; D006056:Golgi Apparatus / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D006801:Humans; D006825:Hybridomas / Q000276:immunology / Q000378:metabolism; D007143:Immunoglobulin Heavy Chains / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D007147:Immunoglobulin Light Chains / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D007135:Immunoglobulin Variable Region / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009844:Oligosaccharides / Q000378:metabolism; D021381:Protein Transport / Q000235:genetics / Q000276:immunology; D014162:Transfection
D022801:Complementarity Determining Regions; D003911:Dextrans; D007143:Immunoglobulin Heavy Chains; D007147:Immunoglobulin Light Chains; D007135:Immunoglobulin Variable Region; D009844:Oligosaccharides; C041999:alpha-1,6-dextran; D001216:Asparagine