The C2 domains of synaptotagmin--partners in exocytosis.
Rapid signaling between neurons relies on the Ca(2+)-triggered exocytosis of neurotransmitters. Release is mediated by 'kiss-and-run' or complete fusion of secretory organelles with the plasma membrane. Current models indicate that exocytosis is regulated by synaptotagmin I (syt) and mediated by SNARE (soluble NSF-attachment protein receptor) proteins. Syt senses Ca(2+) via two conserved motifs, C2A and C2B. C2B engages a wider array of effector molecules than C2A and appears to play a more crucial role in synaptic transmission. However, it has recently become clear that the tandem C2 domains of syt influence each another in unexpected ways. Here, we focus on recent structure-function studies that are beginning to provide insights into the mechanism through which the C2 domains of syt trigger exocytosis.
Bai
Jihong
J
Department of Physiology, University of Wisconsin, 1300 University Avenue, SMI 129, Madison, WI 53706, USA.
Chapman
Edwin R
ER
D002118:Calcium / Q000378:metabolism; D002135:Calcium-Binding Proteins; D005089:Exocytosis; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008954:Models, Biological; D015394:Molecular Structure; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D050600:SNARE Proteins; D050863:Synaptotagmin I; D050857:Synaptotagmins; D033921:Vesicular Transport Proteins
D002135:Calcium-Binding Proteins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D050600:SNARE Proteins; D050863:Synaptotagmin I; D033921:Vesicular Transport Proteins; D050857:Synaptotagmins; D002118:Calcium