Characterization of pro-opiocortin, a precursor to opioid peptides and corticotropin.
The high molecular weight (approximately 30,000) precursor to opioid activity (pro-opiocortin) previously detected in extracts of rat pituitary was digested with trypsin and the resulting peptide mixture was resolved by high-performance reverse-phase chromatography. A peak of opioid activity was eluted at the position of the nonapeptide beta-LPH (61-69), which was also the same fragment obtained by trypsin digestion of betas-lipotropin or beta-endorphin. This identified the protein as a precursor to the endorphins and Met-enkephalin. No activity was detected in the position corresponding to the Leu5 analog of betas-LPH (61-69), thus ruling out the possibility of a beta-lipotropin-like precursor to Leu-enkephalin in pituitary extracts. Pro-opiocortin and beta-lipotropin are present in rat pituitary extracts in comparable amounts, approximately 10 pmol/mg of tissue.
D000324:Adrenocorticotropic Hormone / Q000378:metabolism*; D000818:Animals; D002845:Chromatography; D004723:Endorphins / Q000378:metabolism*; D004745:Enkephalins / Q000378:metabolism; D008970:Molecular Weight; D010902:Pituitary Gland / Q000032:analysis; D011498:Protein Precursors / Q000302:isolation & purification*; D051381:Rats; D014357:Trypsin
D004723:Endorphins; D004745:Enkephalins; D011498:Protein Precursors; D000324:Adrenocorticotropic Hormone; D014357:Trypsin