Monoclonal antibody to peptide sequence of delta opioid receptor inhibits functional coupling of receptor to camp formation

The NG108-15 delta opioid receptor was solubilized and purified to apparent homogeneity .The affinity purified receptor exhibited a single band of 58 KDa and retained the capacity to bind [3H] DADLE with a Kd of 9.5 nM(Gomathi,K.G.and Sharma S.K.,1993,FEES Letts, 330: 146-150). We generated monoclonal antibodies (Mab) to the multiple antigenic peptides of the predicted C-terminal (353T-G367) an<j N-terminal (-L. . . V- ) of the cloned delta opioid receptor .These antibodies immunoprecipitated the delta receptor from crude CHAPS solubilized NG108-15 extracts and the binding of [3H]DPDPE to the immunoprecipitates obtained with C-terminal antibodies exhibited a Kd of 6.4 nM. The N-terminal mab inhibited the functional coupling of the delta receptor to adenylate cyclase as seen by its effect on reversal of PGE stimulated cAMP synthesis. We,thus demonstrate for the first time,an antibody which mimics the opioid ligand. This work is supported by a grant from DBT, Government of India to SKS.