Endocytic active zones: hot spots for endocytosis in vertebrate neuromuscular terminals.
We have used a sensitive activity-dependent probe, sulforhodamine 101 (SR101), to view endocytic events within snake motor nerve terminals. After very brief neural stimulation at reduced temperature, SR101 is visualized exclusively at punctate sites located just inside the presynaptic membrane of each terminal bouton. The number of sites (approximately 26 sites/bouton) and their location (in register with postsynaptic folds) are similar to the number and location of active zones in snake motor terminals, suggesting a spatial association between exocytosis and endocytosis under these stimulus conditions. With more prolonged stimulation, larger SR101-containing structures appear at the bouton margins. Thus endocytosis occurs initially at distinct sites, which we call "endocytic active zones," whereas further stimulation recruits a second endocytic paradigm.
Teng
H
H
Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Cole
J C
JC
Roberts
R L
RL
Wilkinson
R S
RS
D000818:Animals; D001692:Biological Transport / Q000502:physiology; D004396:Coloring Agents / Q000493:pharmacokinetics; D017812:Colubridae; D004705:Endocytosis / Q000502:physiology*; D011992:Endosomes / Q000378:metabolism / Q000648:ultrastructure; D005089:Exocytosis / Q000502:physiology; D016650:Fluorescein-5-isothiocyanate; D005455:Fluorescent Antibody Technique; D005456:Fluorescent Dyes; D008854:Microscopy, Electron; D009469:Neuromuscular Junction / Q000378:metabolism* / Q000648:ultrastructure; D017729:Presynaptic Terminals / Q000378:metabolism* / Q000648:ultrastructure; D012235:Rhodamines / Q000493:pharmacokinetics; D013572:Synaptic Vesicles / Q000378:metabolism / Q000648:ultrastructure; D014714:Vertebrates
D004396:Coloring Agents; D005456:Fluorescent Dyes; D012235:Rhodamines; C050829:sulforhodamine 101; D016650:Fluorescein-5-isothiocyanate