Calcium-independent stimulation of membrane fusion and SNAREpin formation by synaptotagmin I.
J Cell Biol
; 158(2): 273-82, 2002 Jul 22.
Article
em En
| MEDLINE
| ID: mdl-12119360
ABSTRACT
Neurotransmitter release requires the direct coupling of the calcium sensor with the machinery for membrane fusion. SNARE proteins comprise the minimal fusion machinery, and synaptotagmin I, a synaptic vesicle protein, is the primary candidate for the main neuronal calcium sensor. To test the effect of synaptotagmin I on membrane fusion, we incorporated it into a SNARE-mediated liposome fusion assay. Synaptotagmin I dramatically stimulated membrane fusion by facilitating SNAREpin zippering. This stimulatory effect was topologically restricted to v-SNARE vesicles (containing VAMP 2) and only occurred in trans to t-SNARE vesicles (containing syntaxin 1A and SNAP-25). Interestingly, calcium did not affect the overall fusion reaction. These results indicate that synaptotagmin I can directly accelerate SNARE-mediated membrane fusion and raise the possibility that additional components might be required to ensure tight calcium coupling.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Proteínas de Ligação ao Cálcio
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Glicoproteínas de Membrana
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Cálcio
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Proteínas de Transporte Vesicular
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Fusão de Membrana
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Proteínas de Membrana
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Proteínas do Tecido Nervoso
Idioma:
En
Revista:
J Cell Biol
Ano de publicação:
2002
Tipo de documento:
Article
País de afiliação:
Estados Unidos