MOLECULAR-CLONING OF A NOVEL PROTEIN REGULATED BY OPIOID TREATMENT OFNG108-15 CELLS

A new cDNA clone, NGD5, has been identified from a subtraction cDNA li brary constructed with mRNA isolated from control neuroblastoma X glio ma NG108-15 cells and cells treated for 48 h with the delta-opioid ago nist, D-Ala(2), D-Leu(5) enkephalin (DADLE). NGD5 mRNA is decreased, i n a naloxone-reversible manner, upon long-term treatment of NG108-15 c ells with DADLE, indicating that this clone may be related to opioid r eceptor function. Northern analysis indicates that NGD5 mRNA is expres sed in rat brain. Two similar nearly full-length NGD5 clones, NGD5A an d NGD5B, were isolated from a lambda gt10 NG108-15 cDNA library and se quenced. The predicted 40-kDa peptide encoded for by the NGDS cDNA has no significant homology to the recently cloned mu, delta or kappa opi oid receptors nor to any other known proteins.