CLONING AND EXPRESSION OF A CDNA-ENCODING A MOUSE-BRAIN ORPHANIN FQ NOCICEPTIN PRECURSOR

By using a reverse transcription-PCR approach we have cloned a peptide precursor from mouse brain which contains the sequence of orphanin FQ /nociceptin. The mouse sequence of orphanin FQ/nociceptin is identical at the amino acid level with that isolated from rat and porcine brain . Northern analysis of the mRNA encoding the precursor reveals a singl e band of approx. 1 kb, with the highest levels in the brain and much lower levels in kidney and spleen. Southern analysis is consistent wit h a single gene. The precursor peptide from mouse contains two other p utative peptides. Upstream from the orphanin FQ/nociceptin is a 41-ami no-acid peptide which is almost identical, except for a six-amino-acid insertion, with the corresponding 35-amino-acid peptide predicted fro m the rat sequence. Interestingly, the mouse contains a triple AEPGAD repeat within this peptide that is not seen in the rat sequence. Downs tream from the orphanin FQ/nociceptin sequence is another 17-amino-aci d peptide which is identical with that found in the rat.