title: Routing of membrane proteins to large dense core vesicles in PC12 cells.
abstract: Routing of membrane proteins to large dense core vesicles in neuroendocrine cells can depend on information in both the lumenal and cytoplasmic domains. This study in PC12 cells focuses on the routing, cleavage, and secretion of an integral membrane protein, peptidylglycine alpha-amidating monooxygenase (PAM), examining both endogenous and virally derived membrane PAM. The role of the lumenal catalytic domains in membrane PAM trafficking was examined by replacement with an epitope tag. Virally derived membrane PAM is localized to the perinuclear area and to slender processes where the large dense core vesicles are located. Expression of PAM along with a neuroendocrine-specific endoprotease liberates a soluble monooxygenase domain, yielding regulated secretion of both the monooxygenase and the prohormone convertase from large dense core vesicles. The subcellular distribution of the epitope-substituted version of PAM within the cells is similar to that of membrane PAM, and both proteins are internalized from the plasma membrane. When secretion is stimulated, Serine937 in the cytoplasmic domain of PAM is phosphorylated to a similar extent in endogenous membrane PAM, virally encoded membrane PAM, and epitope-substituted PAM. Thus, the lumenal PAM catalytic domains are not required for routing or phosphorylation of PAM in PC12 cells.
authors.affiliation: Department of Neuroscience, University of Connecticut Health Center, Farmington 06030-3401, USA.
authors.forename: Ruth
authors.initials: R
authors.lastname: Marx
authors.forename: Richard E
authors.initials: RE
authors.lastname: Mains
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000256:Adenoviridae / Q000235:genetics / Q000378:metabolism; D000818:Animals; D016282:Aspartic Acid Endopeptidases / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D002451:Cell Compartmentation / Q000502:physiology; D002467:Cell Nucleus / Q000378:metabolism / Q000648:ultrastructure; D000939:Epitopes / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D005822:Genetic Vectors / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism*; D006899:Mixed Function Oxygenases / Q000235:genetics / Q000378:metabolism*; D009097:Multienzyme Complexes / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000201:enzymology* / Q000648:ultrastructure; D009490:Neurosecretory Systems / Q000201:enzymology* / Q000648:ultrastructure; D016716:PC12 Cells; D010766:Phosphorylation; D043484:Proprotein Convertases; D020033:Protein Isoforms; D017434:Protein Structure, Tertiary / Q000502:physiology; D021381:Protein Transport / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D022142:Secretory Vesicles / Q000201:enzymology* / Q000648:ultrastructure; D013347:Subcellular Fractions / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D000939:Epitopes; D008565:Membrane Proteins; D009097:Multienzyme Complexes; D020033:Protein Isoforms; D012333:RNA, Messenger; D006899:Mixed Function Oxygenases; C035189:peptidylglycine monooxygenase; C114022:MYCBP2 protein, human; D044767:Ubiquitin-Protein Ligases; D043484:Proprotein Convertases; D016282:Aspartic Acid Endopeptidases