Synaptotagmin I: a major Ca2+ sensor for transmitter release at a central synapse.
Mice carrying a mutation in the synaptotagmin I gene were generated by homologous recombination. Mutant mice are phenotypically normal as heterozygotes, but die within 48 hr after birth as homozygotes. Studies of hippocampal neurons cultured from homozygous mutant mice reveal that synaptic transmission is severely impaired. The synchronous, fast component of Ca(2+)-dependent neurotransmitter release is decreased, whereas asynchronous release processes, including spontaneous synaptic activity (miniature excitatory postsynaptic current frequency) and release triggered by hypertonic solution or alpha-latrotoxin, are unaffected. Our findings demonstrate that synaptotagmin I function is required for Ca2+ triggering of synchronous neurotransmitter release, but is not essential for asynchronous or Ca(2+)-independent release. We propose that synaptotagmin I is the major low affinity Ca2+ sensor mediating Ca2+ regulation of synchronous neurotransmitter release in hippocampal neurons.
Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas 75235.
M
M
Geppert
Y
Y
Goda
R E
RE
Hammer
C
C
Li
T W
TW
Rosahl
C F
CF
Stevens
T C
TC
Südhof
D000818:Animals; D000831:Animals, Newborn; D001483:Base Sequence; D001921:Brain / Q000502:physiology*; D002118:Calcium / Q000378:metabolism*; D002135:Calcium-Binding Proteins; D017931:DNA Primers; D005091:Exons; D006624:Hippocampus / Q000502:physiology*; D006720:Homozygote; D006982:Hypertonic Solutions; D008562:Membrane Glycoproteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D051379:Mice; D008818:Mice, Neurologic Mutants; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D018377:Neurotransmitter Agents / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D012016:Reference Values; D015183:Restriction Mapping; D013111:Spider Venoms / Q000494:pharmacology; D013569:Synapses / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology; D050863:Synaptotagmin I; D050857:Synaptotagmins
D002135:Calcium-Binding Proteins; D017931:DNA Primers; D006982:Hypertonic Solutions; D008562:Membrane Glycoproteins; D009419:Nerve Tissue Proteins; D018377:Neurotransmitter Agents; D013111:Spider Venoms; D050863:Synaptotagmin I; C494311:Syt1 protein, mouse; D050857:Synaptotagmins; C020763:alpha-latrotoxin; D002118:Calcium