title: Oligomerization of pro-opiomelanocortin is independent of pH, calcium and the sorting signal for the regulated secretory pathway.
abstract: Studies indicate that pro-opiomelanocortin (POMC) is sorted to the regulated secretory pathway by binding to a sorting receptor identified as membrane-bound carboxypeptidase E (CPE) [Cool et al. (1997) Cell 88, 73-83]. The efficiency of this sorting mechanism could be enhanced if POMC molecules were to self-associate to form oligomers, prior or subsequent to binding to CPE. Using cross-linking and gel filtration techniques, we demonstrated that POMC forms oligomers at both neutral and acidic pHs and calcium was not necessary. delta N-POMC, which lacks the N-terminal sorting signal for the regulated secretory pathway, also formed similar oligomers, indicating that the sorting and oligomerization domains are different.
authors.affiliation: Section on Cellular Neurobiology, Laboratory of Developmental Neurobiology, Bldg. 49/Rm 5A38, National Institute for Child and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: N X
authors.initials: NX
authors.lastname: Cawley
authors.forename: E
authors.initials: E
authors.lastname: Normant
authors.forename: A
authors.initials: A
authors.lastname: Chen
authors.forename: Y P
authors.initials: YP
authors.lastname: Loh
mesh_terms: D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D015153:Blotting, Western; D002118:Calcium / Q000494:pharmacology*; D043423:Carboxypeptidase H; D002268:Carboxypeptidases / Q000378:metabolism; D002460:Cell Line; D002850:Chromatography, Gel; D003432:Cross-Linking Reagents; D006863:Hydrogen-Ion Concentration; D008970:Molecular Weight; D011333:Pro-Opiomelanocortin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects; D021382:Protein Sorting Signals / Q000235:genetics / Q000502:physiology*; D020836:Protein Structure, Quaternary / Q000187:drug effects; D017384:Sequence Deletion / Q000235:genetics; D018411:Spodoptera; D014162:Transfection
chemical_list: D003432:Cross-Linking Reagents; D021382:Protein Sorting Signals; D011333:Pro-Opiomelanocortin; D002268:Carboxypeptidases; D043423:Carboxypeptidase H; D002118:Calcium