Three-dimensional structure of the synaptotagmin 1 C2B-domain: synaptotagmin 1 as a phospholipid binding machine.
Fernandez, I., Arac, D., Ubach, J., Gerber, S.H., Shin, O., Gao, Y., Anderson, R.G., Sudhof, T.C., Rizo, J.(2001) Neuron 32: 1057-1069
- PubMed: 11754837 
- DOI: https://doi.org/10.1016/s0896-6273(01)00548-7
- Primary Citation of Related Structures:  
1K5W - PubMed Abstract: 
Synaptotagmin 1 probably functions as a Ca2+ sensor in neurotransmitter release via its two C2-domains, but no common Ca2+-dependent activity that could underlie a cooperative action between them has been described. The NMR structure of the C2B-domain now reveals a beta sandwich that exhibits striking similarities and differences with the C2A-domain. Whereas the bottom face of the C2B-domain has two additional alpha helices that may be involved in specialized Ca2+-independent functions, the top face binds two Ca2+ ions and is remarkably similar to the C2A-domain. Consistent with these results, but in contrast to previous studies, we find that the C2B-domain binds phospholipids in a Ca2+-dependent manner similarly to the C2A-domain. These results suggest a novel view of synaptotagmin function whereby the two C2-domains cooperate in a common activity, Ca2+-dependent phospholipid binding, to trigger neurotransmitter release.
Organizational Affiliation: 
Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.