Experimental Data Snapshot

  • Resolution: 3.20 Å
  • R-Value Free: 0.348 
  • R-Value Work: 0.293 
  • R-Value Observed: 0.293 

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Crystal structure of the cytosolic C2A-C2B domains of synaptotagmin III. Implications for Ca(+2)-independent snare complex interaction.

Sutton, R.B.Ernst, J.A.Brunger, A.T.

(1999) J Cell Biol 147: 589-598

  • DOI: https://doi.org/10.1083/jcb.147.3.589
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    Synaptotagmins are synaptic vesicle-associated, phospholipid-binding proteins most commonly associated with Ca(+2)-dependent exocytotic and Ca(+2)- independent endocytotic events. Synaptotagmin III is a 63.2-kD member of the synaptotagmin homology group; one of its characteristic properties is the ability to bind divalent cations and accessory proteins promiscuously. In the cytosolic portion of this protein, a flexible seven-amino acid linker joins two homologous C2 domains. The C2A domain binds to phospholipid membranes and other accessory proteins in a divalent cation-dependent fashion. The C2B domain promotes binding to other C2B domains, as well as accessory proteins independent of divalent cations. The 3.2 A crystal structure of synaptotagmin III, residues 295-566, which includes the C2A and C2B domains, exhibits differences in the shape of the Ca(+2)-binding pocket, the electrostatic surface potential, and the stoichiometry of bound divalent cations for the two domains. These observations may explain the disparate binding properties of the two domains. The C2A and the C2B domains do not interact; synaptotagmin, therefore, covalently links two independent C2 domains, each with potentially different binding partners. A model of synaptotagmin's involvement in Ca(+2)-dependent regulation of membrane fusion through its interaction with the SNARE complex is presented.

  • Organizational Affiliation

    The Howard Hughes Medical Institute, Yale University, New Haven, Connecticut 06520, USA.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
SYNAPTOTAGMIN III296Rattus rattusMutation(s): 0 
Find proteins for P40748 (Rattus norvegicus)
Explore P40748 
Go to UniProtKB:  P40748
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP40748
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 3.20 Å
  • R-Value Free: 0.348 
  • R-Value Work: 0.293 
  • R-Value Observed: 0.293 
  • Space Group: P 62 2 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 125.959α = 90
b = 125.959β = 90
c = 118.438γ = 120
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2000-01-19
    Type: Initial release
  • Version 1.1: 2008-04-27
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2024-02-07
    Changes: Data collection, Database references, Derived calculations