Macromolecular connections of active zone material to docked synaptic vesicles and presynaptic membrane at neuromuscular junctions of mouse.
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.
Nagwaney
Sharuna
S
Department of Neurobiology, Stanford University School of Medicine, Stanford, California 94305, USA.
Harlow
Mark Lee
ML
Jung
Jae Hoon
JH
Szule
Joseph A
JA
Ress
David
D
Xu
Jing
J
Marshall
Robert M
RM
McMahan
Uel Jackson
UJ
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*
D046911:Macromolecular Substances