title: Regulation of large dense-core vesicle volume and neurotransmitter content mediated by adaptor protein 3.
abstract: Adaptor protein 3 (AP-3) is a vesicle-coat protein that forms a heterotetrameric complex. Two types of AP-3 subunits are found in mammalian cells. Ubiquitous AP-3 subunits are expressed in all tissues of the body, including the brain. In addition, there are neuronal AP-3 subunits that are thought to serve neuron-specific functions such as neurotransmitter release. In this study, we show that overexpression of neuronal AP-3 in mouse chromaffin cells results in a striking decrease in the neurotransmitter content of individual vesicles (quantal size), whereas deletion of all AP-3 produces a dramatic increase in quantal size; these changes were correlated with alterations in dense-core vesicle size. AP-3 appears to localize in the trans-Golgi network and possibly immature secretory vesicles, where it may be involved in the formation of neurosecretory vesicles.
authors.affiliation: Department of Neurobiology, Pharmacology, and Physiology, University of Chicago, 947 East 58th Street, Chicago, IL 60637, USA.
authors.forename: Chad P
authors.initials: CP
authors.lastname: Grabner
authors.forename: Steven D
authors.initials: SD
authors.lastname: Price
authors.forename: Anna
authors.initials: A
authors.lastname: Lysakowski
authors.forename: Anne L
authors.initials: AL
authors.lastname: Cahill
authors.forename: Aaron P
authors.initials: AP
authors.lastname: Fox
mesh_terms: D033963:Adaptor Protein Complex 3 / Q000235:genetics / Q000502:physiology*; D000818:Animals; D002478:Cells, Cultured; D019439:Chromaffin Cells / Q000378:metabolism / Q000648:ultrastructure*; D051379:Mice; D008817:Mice, Mutant Strains; D009154:Mutation; D009474:Neurons / Q000378:metabolism / Q000648:ultrastructure; D018377:Neurotransmitter Agents / Q000378:metabolism*; D022142:Secretory Vesicles / Q000378:metabolism / Q000648:ultrastructure*; D017384:Sequence Deletion; D015533:Transcriptional Activation; D021601:trans-Golgi Network / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D033963:Adaptor Protein Complex 3; D018377:Neurotransmitter Agents