Presynaptic injection of syntaxin-specific antibodies blocks transmission in the squid giant synapse.
A polyclonal antibody, raised against the squid (Loligo pealei) syntaxin I, inhibited Ca2+-dependent interaction of syntaxin with synaptotagmin C2A domain in vitro. Presynaptic injection of the anti-Loligo syntaxin IgG into the squid giant synapse blocked synaptic transmission without affecting the presynaptic action potential or the voltage-gated calcium current responsible for transmitter release. Repetitive presynaptic stimulation produced a gradual decrease in the amplitude of the postsynaptic potential as the synaptic block progressed, indicating that the antibody interferes with vesicular fusion. Confocal microscopy of the fluorescein-labelled anti-Loligo syntaxin IgG showed binding at the synaptic active zone, while ultrastructurally, an increase in synaptic vesicular numbers in synapses blocked when this antibody was observed. These results implicate syntaxin in the vesicular fusion step of transmitter release in concert with synaptotagmin.
Sugimori
M
M
Department of Physiology and Neuroscience, New York University Medical Center, NY 10016, USA.
Tong
C K
CK
Fukuda
M
M
Moreira
J E
JE
Kojima
T
T
Mikoshiba
K
K
Llinás
R
R
D000595:Amino Acid Sequence; D000818:Animals; D001369:Axons / Q000502:physiology / Q000648:ultrastructure; D001483:Base Sequence; D002118:Calcium / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000378:metabolism; D003001:Cloning, Molecular; D049832:Decapodiformes; D007074:Immunoglobulin G / Q000494:pharmacology*; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008959:Models, Neurological; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000378:metabolism; D050765:Qa-SNARE Proteins; D051381:Rats; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013569:Synapses / Q000502:physiology* / Q000648:ultrastructure; D009435:Synaptic Transmission / Q000502:physiology*; D013572:Synaptic Vesicles / Q000502:physiology; D050857:Synaptotagmins
D002135:Calcium-Binding Proteins; D007074:Immunoglobulin G; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D050765:Qa-SNARE Proteins; D011994:Recombinant Proteins; D050857:Synaptotagmins; D002118:Calcium