DEVELOPMENT AND CHARACTERIZATION OF ANTIBODIES AGAINST THE N-TERMINUSOF THE HUMAN DOPAMINE-D4 RECEPTOR

The human dopamine D4 receptor (hD4R), which has been implicated in hu man diseases such as schizophrenia and in a personality trait called ' 'novelty seeking,'' has not yet been characterized at the protein leve l. Following epitope scanning of the hD4R, we have produced a highly s pecific monoclonal antibody named DFR1 raised against an amino-termina l peptide in a predicted extracellular region of the receptor. DFR1 de corated recombinant hD4Rs on the surface of intact Chinese hamster ova ry (CHO) cells by flow cytometry and fluorescence microscopy and also recognized recombinant hD4.2, hD4.4, and hD4.7 receptor isoforms by we stern blot analysis, When expressed stably in CHO cells, all three hD4 R isoforms contained N-linked glycosylation and showed apparent molecu lar masses of 48, 55, and 67 kDa for hD4.2, hD4.4, and hD4.7, respecti vely. DFR1 immunoreactivity representing hD4R protein or dopamine D4 r eceptor-like antigens was observed in crude membrane extracts of postm ortem human brain tissue by immunoblotting, The DFR1 antibody provides a new immunological tool with the potential to further our understand ing of the human dopamine D4 receptor protein.