title: Macromolecular connections of active zone material to docked synaptic vesicles and presynaptic membrane at neuromuscular junctions of mouse.
abstract: Electron tomography was used to view macromolecules composing active zone material (AZM) in axon terminals at mouse neuromuscular junctions. Connections of the macromolecules to each other, to calcium channels in the presynaptic membrane, and to synaptic vesicles docked on the membrane prior to fusing with it during synaptic transmission were similar to those of AZM macromolecules at frog neuromuscular junctions previously examined by electron tomography and support the hypothesis that AZM regulates vesicle docking and fusion. A species difference in the arrangement of AZM relative to docked vesicles may help account for a greater vesicle-presynaptic membrane contact area during docking and a greater probability of fusion during synaptic transmission in mouse. Certain AZM macromolecules in mouse were connected to synaptic vesicles contacting the presynaptic membrane at sites where fusion does not occur. These secondary docked vesicles had a different relationship to the membrane and AZM macromolecules than primary docked vesicles, consistent with their having a different AZM-regulated behavior.
authors.affiliation: Department of Neurobiology, Stanford University School of Medicine, Stanford, California 94305, USA.
authors.forename: Sharuna
authors.initials: S
authors.lastname: Nagwaney
authors.forename: Mark Lee
authors.initials: ML
authors.lastname: Harlow
authors.forename: Jae Hoon
authors.initials: JH
authors.lastname: Jung
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Szule
authors.forename: David
authors.initials: D
authors.lastname: Ress
authors.forename: Jing
authors.initials: J
authors.lastname: Xu
authors.forename: Robert M
authors.initials: RM
authors.lastname: Marshall
authors.forename: Uel Jackson
authors.initials: UJ
authors.lastname: McMahan
mesh_terms: D000818:Animals; D055032:Electron Microscope Tomography; D046911:Macromolecular Substances / Q000032:analysis*; D051379:Mice; D008810:Mice, Inbred C57BL; D009469:Neuromuscular Junction / Q000737:chemistry / Q000502:physiology / Q000648:ultrastructure*; D017729:Presynaptic Terminals / Q000737:chemistry / Q000502:physiology / Q000648:ultrastructure*; D013569:Synapses / Q000737:chemistry / Q000502:physiology / Q000648:ultrastructure*; D013572:Synaptic Vesicles / Q000737:chemistry / Q000502:physiology / Q000648:ultrastructure*
chemical_list: D046911:Macromolecular Substances