Molecular cloning of a monoclonal anti-tumor antibody specific for the Tn antigen and expression of an active single-chain Fv fragment.
We report here the first amino acid sequence of an anti-Tn monoclonal antibody raised against human breast cancer cells and show that a single chain Fv fragment of this IgM retains the Tn-binding specificity as defined by functional assays with asialo-OSM and membrane extracts from MCF-7 cells. Sequence comparisons and molecular modeling of 83D4 indicate that the antibody combining site displays a cavity-like feature primarily defined by the CDR H1 and H2 loops. This pocket could accommodate a single Tn molecule, thus, suggesting a structural explanation for the predominant expression of a particular VH gene segment in a group of antibodies that recognize tumor-associated antigens arising from an aberrant O-glycosylation.
Babino
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A
Departamento de Bioquímica, Facultad de Medicina, Montevideo, Uruguay.
Pritsch
O
O
Oppezzo
P
P
Du Pasquier
R
R
Roseto
A
A
Osinaga
E
E
Alzari
P M
PM
D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000235:genetics / Q000276:immunology*; D000912:Antibodies, Neoplasm / Q000235:genetics / Q000276:immunology*; D000918:Antibody Specificity; D015295:Antigens, Tumor-Associated, Carbohydrate / Q000235:genetics / Q000276:immunology*; D001483:Base Sequence; D001943:Breast Neoplasms / Q000276:immunology; D002277:Carcinoma / Q000276:immunology; D003001:Cloning, Molecular; D005784:Gene Amplification; D006801:Humans; D006825:Hybridomas; D007128:Immunoglobulin Fragments / Q000235:genetics / Q000276:immunology*; D007075:Immunoglobulin M / Q000235:genetics / Q000276:immunology*; D007135:Immunoglobulin Variable Region / Q000235:genetics / Q000276:immunology*; D007145:Immunoglobulin kappa-Chains / Q000235:genetics / Q000276:immunology*; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011993:Recombinant Fusion Proteins; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D014407:Tumor Cells, Cultured
D000911:Antibodies, Monoclonal; D000912:Antibodies, Neoplasm; D015295:Antigens, Tumor-Associated, Carbohydrate; D007128:Immunoglobulin Fragments; D007075:Immunoglobulin M; D007135:Immunoglobulin Variable Region; D007145:Immunoglobulin kappa-Chains; D011993:Recombinant Fusion Proteins; C040286:Tn antigen