CLONING, CHARACTERIZATION, AND MODELING OF A MONOCLONAL ANTI-HUMAN TRANSFERRIN ANTIBODY THAT COMPETES WITH THE TRANSFERRIN RECEPTOR

In this report we describe the isolation and characterization of a mon oclonal antibody against human serum transferrin (Tf) and the cloning and sequencing of its cDNA. The antibody competes with the transferrin receptor (TR) for binding to human Tf and is therefore expected to bi nd at or very close to a region of interaction between Tf and its rece ptor. From the deduced amino acid sequence, we constructed a 3-dimensi onal model of the variable domains of the antibody based on the canoni cal structure model for the hypervariable loops. The proposed structur e of the antibody is a first step toward a more detailed characterizat ion of the antibody-Tf complex and possibly toward a better understand ing of the Tf interaction with its receptor. The model might prove use ful in guiding site-directed mutagenesis studies, simplifying the expe rimental elucidation of the antibody structure, and in the use of auto matic procedures to dock the interacting molecules as soon as structur al information about the structure of the human Tf molecule will be av ailable.