N-glycosylation is essential for vesicular targeting of synaptotagmin 1

Neuron. 2004 Jan 8;41(1):85-99. doi: 10.1016/s0896-6273(03)00820-1.

Abstract

Synaptotagmins 1 and 7 are candidate Ca(2+) sensors for exocytosis localized to synaptic vesicles and plasma membranes, respectively. We now show that the N-terminal intraluminal sequence of synaptotagmin 1, when transplanted onto synaptotagmin 7, redirects synaptotagmin 7 from the plasma membrane to secretory vesicles. Conversely, mutation of the N-terminal N-glycosylation site of synaptotagmin 1 redirects synaptotagmin 1 from vesicles to the plasma membrane. In cultured hippocampal neurons, the plasma membrane-localized mutant of synaptotagmin 1 suppressed the readily releasable pool of synaptic vesicles, whereas wild-type synaptotagmin 1 did not. In addition to the intraluminal N-glycosylation site, the cytoplasmic C(2) domains of synaptotagmin 1 were required for correct targeting but could be functionally replaced by the C(2) domains of synaptotagmin 7. Our data suggest that the intravesicular N-glycosylation site of synaptotagmin 1 collaborates with its cytoplasmic C(2) domains in directing synaptotagmin 1 to synaptic vesicles via a novel N-glycosylation-dependent mechanism.

MeSH terms

  • Aging / metabolism
  • Animals
  • Biological Transport / genetics
  • Calcium-Binding Proteins / genetics
  • Calcium-Binding Proteins / metabolism
  • Calcium-Binding Proteins / physiology*
  • Cell Line
  • Cytoplasm / metabolism
  • Genetic Vectors
  • Glycosylation*
  • Membrane Glycoproteins / genetics
  • Membrane Glycoproteins / metabolism
  • Membrane Glycoproteins / physiology*
  • Mice
  • Mice, Knockout
  • Mutation / physiology
  • Nerve Tissue Proteins / genetics
  • Nerve Tissue Proteins / metabolism
  • Nerve Tissue Proteins / physiology*
  • Neurosecretory Systems / cytology
  • Neurosecretory Systems / metabolism
  • Neurotransmitter Agents / metabolism
  • PC12 Cells
  • Protein Structure, Tertiary
  • Rats
  • Semliki forest virus / genetics
  • Synaptic Vesicles / physiology*
  • Synaptotagmin I
  • Synaptotagmins
  • Transfection

Substances

  • Calcium-Binding Proteins
  • Membrane Glycoproteins
  • Nerve Tissue Proteins
  • Neurotransmitter Agents
  • Synaptotagmin I
  • Syt1 protein, mouse
  • Syt1 protein, rat
  • Synaptotagmins