"Joining peptide" of pro-opiomelanocortin. I. Radioimmunoassay and extraction of related peptides from pituitary glands.
In order to immunoassay the specific region of bovine pituitary pro-opiomelanocortin (POMC) between ACTH and gamma-MSH, referred to as "joining peptide," antisera were prepared against the synthetic amidated decapeptide Val-Ala-Val-Gly-Glu-Gly-Pro-Gly-Pro-Arg-NH2. The non-amidated peptide represents residues -23 to -14 of bovine POMC. An NH2-terminal tyrosine analog of the decapeptide was used as the radioligand. Under optimal conditions, immunoassay with selected antisera exhibited a sensitivity (50% displacement of the radioligand) toward the decapeptide in the range of 31-55 pg. Immunoreactivity found in extracts of fresh or lyophilized bovine pituitary glands displaced the iodinated Tyr-decapeptide in the RIA in a parallel manner. The amount of immunoreactive (ir)-material was dependent upon the state of preservation of the tissue, the method of extraction, and the particular antiserum used. Extractable immunoreactivity was separated into low (Mr 1,500) and high (Mr 17,000) molecular weight peptides using gel chromatography (G-75). Additional ir-material appeared in the void volume (Mr greater than 22,500). Thus, these antisera have the capacity to interact not only with a region of the joining peptide but also with its larger, and apparent precursor forms. The immunoassay developed should be valuable in understanding the disposition and processing in this specific region of POMC.
D000818:Animals; D002417:Cattle; D006863:Hydrogen-Ion Concentration; D008970:Molecular Weight; D009842:Oligopeptides / Q000032:analysis*; D009928:Organ Specificity; D009994:Osmolar Concentration; D010446:Peptide Fragments / Q000032:analysis*; D010455:Peptides / Q000302:isolation & purification; D010902:Pituitary Gland / Q000032:analysis*; D010903:Pituitary Gland, Anterior / Q000032:analysis*; D010908:Pituitary Hormones, Anterior / Q000032:analysis*; D011333:Pro-Opiomelanocortin; D011498:Protein Precursors / Q000032:analysis*; D011863:Radioimmunoassay / Q000379:methods; D013329:Structure-Activity Relationship
D009842:Oligopeptides; D010446:Peptide Fragments; D010455:Peptides; D010908:Pituitary Hormones, Anterior; D011498:Protein Precursors; D011333:Pro-Opiomelanocortin; C039934:pro-opiomelanocortin joining peptide(14-23)